4. General Structure of the Input File¶

In general, the input file is a free format ASCII file and can contain one or more keyword lines that start with a “!” sign, one or more input blocks enclosed between an “%” sign and “end” that provide finer control over specific aspects of the calculation, and finally the specification of the coordinates for the system along with the charge and multiplicity provided either with a %coords block, or more usually enclosed within two “*” symbols. Here is an example of a simple input file that contains all three input elements:

! HF def2-TZVP

%scf
   convergence tight
end

* xyz 0 1
C  0.0  0.0  0.0
O  0.0  0.0  1.13
*

Comments in the file start by a “#”. For example:

# This is a comment. Continues until the end of the line

Comments can also be closed by a second “#”, as the example below where TolE and TolMaxP are two variables that can be user specified:

TolE=1e-5;    #Energy conv.#  TolMaxP=1e-6; #Density conv.#

The input may contain several blocks, which consist of logically related data that can be user controlled. The program tries to choose sensible default values for all of these variables. However, it is impossible to give defaults that are equally sensible for all systems. In general the defaults are slightly on the conservative side and more aggressive cutoffs etc. can be chosen by the user and may help to speed things up for actual systems or give higher accuracy if desired.

4.1. Input Blocks¶

The following blocks exist:

`autoci`	Controls autogenerated correlation calculations
`basis`	Basis sets are specified
`casresp`	Control of CASSCF static linear response calculations
`casscf`	Control of CASSCF/NEVPT2 and DMRG calculations
`cipsi`	Control of Iterative-Configuration Expansion Configuration Interaction calculation
`cim`	Control of Cluster In Molecules calculations
`cis`	Control of CIS and TD-DFT calculations (synonym is `tddft`)
`coords`	Input of atomic coordinates
`compound`	Control of compound
`cosmors`	Control of ORCA/COSMO-RS calculations
`cpcm`	Control of the Conductor-like Polarizable Continuum Model
`elprop`	Control of electric property calculations
`eprnmr`	Control of EPR and NMR calculations
`esd`	Control of ESD calculations
`freq`	Control of frequency calculations
`geom`	Control of geometry optimization
`irc`	Control of intrinsic reaction coordinate calculations
`loc`	Localization of orbitals
`mcrpa`	Control CASSCF linear response calculations
`md`	Control of molecular dynamics simulation
`mdci`	Controls single reference correlation methods
`method`	Here a computation method is specified
`mp2`	Controls the details of the MP2 calculation
`mrcc`	Control of multi-reference CC calculations
`mrci`	Control of MRCI calculations
`neb`	Control of NEB calculations
`numgrad`	Control of numerical gradients
`nbo`	Controls NBO analysis with GENNBO
`output`	Control of output
`pal`	Control of parallel jobs
`paras`	Input of semi-empirical parameters
`plots`	Control of plot generation
`rel`	Control of relativistic options
`rocis`	Control of restricted-open-shell CIS
`rr`	Control of resonance Raman and absorption/fluorescence band-shape calculations
`scf`	Control of the SCF procedure
`symmetry`	Control of spatial symmetry recognition

Blocks start with “%” and end with “end”. Note that input is not case sensitive. For example:

%method  method HF
         end

No blocks need to be present in an input file but they can be present if detailed control over the behavior of the program is desired. Otherwise all normal jobs can be defined via the keywords described in the next section. Variable assignments have the following general structure:

VariableName Value

Some variables are actually arrays. In this case several possible assignments are useful:

Array[1]  Value1
Array[1]  Value1,Value2,Value3
Array  Value1,Value2

Note

Arrays always start with index 0 in ORCA (this is because ORCA is a C++ program). The first line in the example gives the value “Value1” to Array[1], which is the second member of this array. The second line assigns Value1 to Array[1], Value2 to Array[2] and Value3 to Array[3]. The third line assigns Value1 to Array[0] and Value2 to Array[1].

Strings (for examples filenames) must be enclosed in quotes. For example:

MOInp  "Myfile.gbw"

In general the input is not case sensitive. However, inside strings the input is case sensitive. This is because on unix systems MYFILE.GBW and MyFile.gbw are different files. Under Windows the file names are not case sensitive.

4.2. Keyword Lines¶

It is possible to give a line of keywords that assign certain variables that normally belong to different input blocks. The syntax for this “simple input” is line-oriented. A keyword line starts with the “!” sign.

! Keywords

4.2.1. Main Methods and Options¶

Table 4.1 provides a list of keywords that can be used within the “simple input” keyword line to request specific methods and/or algorithmic options. Most of them are self-explanatory. The others are explained in detail in the section of the manual that deals with the indicated input block.

Table 4.1 Main keywords that can be used in the simple input of ORCA.¶
Keyword	Input block	Variable	Comment
HF	METHOD	METHOD	Selects the Hartree-Fock method
DFT			Selects the DFT method (see section Density Functional Methods for a list of functionals)
FOD			FOD analysis (see Fractional Occupation Number Weighted Electron Density (FOD)) employing default settings (TPSS/def2-TZVP, TightSCF, SmearTemp = 5000 K)

4.2.1.1. Runtypes¶

Keyword	Input block	Variable	Comment
ENERGY or SP	METHOD	RUNTYP	Selects a single point calculation
OPT			Selects a geometry optimization calculation (using 2022 internal redundant coordinates)
COPT			Optimization in Cartesian coordinates (if you are desperate)
ENGRAD			Selects an energy and gradient calculation
NUMGRAD			Numerical gradient (has explicitly to be asked for, if analytic gradient is not available)
NUMFREQ			Numerical frequencies
NUMNACME			Numerical non-adiabatic coplings (only for CIS/TD-DFT)
MD			Molecular dynamic simulation
CIM			Cluster-In-Molecule calculation

4.2.1.2. Atomic mass/weight handling¶

Keyword	Input block	Variable	Comment
Mass2016	METHOD	AMASS	Use the latest (2016) atomic masses of the most abundant or most stable isotopes instead of atomic weights.
PAF			Shift and rotate the molecule into its principle axis frame using the 2016 atomic masses by default.

4.2.1.3. Symmetry handling¶

Keyword	Input block	Variable	Comment
UseSym			Turns on the use of molecular symmetry (see section ORCA and Symmetry). THIS IS VERY RUDIMENTARY!
NoUseSym			Turns symmetry off

4.2.1.4. Second order many body perturbation theory¶

Keyword	Input block	Variable	Comment
MP2			Selects Method=HF and DoMP2=true
MP2RI or RI-MP2			Select the MP2-RI method
SCS-MP2			Spin-component scaled MP2
RI-SCS-MP2			Spin-component scaled RI-MP2
			(synonym is SCS-RI-MP2)
OO-RI-MP2			Orbital optimized RI-MP2
OO-RI-SCS-MP2			Orbital optimized and spin-component scaled RI-MP2
MP2-F12			MP2 with F12 correction
			(synonym is F12-MP2)
MP2-F12-RI			MP2-RI with RI-F12 correction
MP2-F12D-RI			MP2-RI with RI-F12 correction employing the D approximation (less expensive), (synonyms are F12-RI-MP2, RI-MP2-F12)

4.2.1.5. High-level single reference methods¶

These are implemented in the MDCI module. They can be run in a number of technical variants.

Keyword	Input block	Variable	Comment
CCSD	MDCI	CITYPE	Coupled-cluster singles and doubles
CCSD(T)			Same with perturbative triples correction
CCSD-F12			CCSD with F12 correction
CCSD(T)-F12			CCSD(T) with F12 correction
CCSD-F12/RI			CCSD with RI-F12 correction
CCSD-F12D/RI			CCSD with RI-F12 correction employing the D approximation (less expensive)
CCSD(T)-F12/RI			CCSD(T) with RI-F12 correction
CCSD(T)-F12D/RI			CCSD(T) with RI-F12 correction employing the D approximation (less expensive)
QCISD			Quadratic Configuration interaction
QCISD(T)			Same with perturbative triples correction
QCISD-F12			QCISD with F12 correction
QCISD(T)-F12			QCISD(T) with F12 correction
QCISD-F12/RI			QCISD with RI-F12 correction
QCISD(T)-F12/RI			QCISD(T) with RI-F12 correction
NCPF/1			A “new” modified coupled-pair functional
CEPA/1			Coupled-electron-pair approximation
NCEPA/1			The CEPA analogue of NCPF/1
RI-CEPA/1-F12			RI-CEPA with F12 correction
MP3			MP3 energies
SCS-MP3			Grimme’s refined version of MP3

Other coupled-pair methods are available and are documented later in the manual in detail (section 7.8) In general you can augment the method with RI-METHOD in order to make the density fitting approximation operative; RI34-METHOD does the same but only for the 3- and 4-external integrals). MO-METHOD performs a full four index transformation and AO-METHOD computes the 3- and 4-external contributions on the fly. With AOX-METHOD this is is done from stored AO integrals.

4.2.1.6. AUTOCI single reference methods¶

These single reference correlation methods are available in the AUTOCI.

Keyword	Input block	Variable	Comment
AUTOCI-CID	AUTOCI	CITYPE	Configuration Interaction with doubles
AUTOCI-CISD			CI with singles and doubles
AUTOCI-CISDT			CI with singles, doubles and triples
AUTOCI-CEPA(0)			Zeroth-order Coupled-Electron pair approximation
AUTOCI-CCD			Coupled-Cluster with doubles
AUTOCI-CCSD			Coupled-Cluster with singles, doubles
AUTOCI-CCSDT			Coupled-Cluster with singles, doubles, triples
AUTOCI-CCSDT-1			Approximate CCSDT-1 model
AUTOCI-CCSDT-2			Approximate CCSDT-2 model
AUTOCI-CCSDT-3			Approximate CCSDT-3 model
AUTOCI-CCSDT-4			Approximate CCSDT-4 model
AUTOCI-QCISD			Quadratic CISD model
AUTOCI-CC2			Approximate CC with singles, doubles
AUTOCI-CC3			Approximate CC with singles, doubles, triples
AUTOCI-CCSD(T)			Coupled-Cluster with singles, doubles and pertubative triples
AUTOCI-CCSD[T]			Coupled-Cluster with singles, doubles and pertubative triples
AUTOCI-MP2			Second-order Moller-Plesset PT
AUTOCI-MP3			Third-order Moller-Plesset PT
AUTOCI-MP4(SDQ)			Fourth-order Moller-Plesset PT without triples
AUTOCI-MP4			Forth-order Moller-Plesset PT
AUTOCI-MP5			Fifth-order Moller-Plesset PT

4.2.1.7. Local correlation methods¶

These are local, pair natural orbital based correlation methods. They must be used together with auxiliary correlation fitting basis sets. Open-shell variants are available for some of the methods, for full list please see section Coupled-Cluster and Coupled-Pair Methods.

Keyword	Input block	Variable	Comment
DLPNO-CCSD			Domain based local pair natural orbital coupled-cluster method with single and double excitations (closed-shell only)
DLPNO-CCSD(T)			DLPNO-CCSD with perturbative triple excitations
DLPNO-CCSD(T1)			DLPNO-CCSD with iterative perturbative triple excitations
DLPNO-MP2	MP2	Various	Local (DLPNO) MP2
DLPNO-SCS-MP2			Spin-component scaled DLPNO-MP2
			(a synonym is SCS-DLPNO-MP2)
DLPNO-MP2-F12			DLPNO-MP2 with F12 correction employing an efficient form of the C approximation
DLPNO-MP2-F12/D			DLPNO-MP2-F12 with approach D (less expensive than the C approximation)
DLPNO-CCSD-F12			DLPNO-CCSD with F12 correction employing an efficient form of the C approximation
DLPNO-CCSD-F12/D			DLPNO-CCSD-F12 with approach D (less expensive than the C approximation)
DLPNO-CCSD(T)-F12			DLPNO-CCSD(T) with F12 correction employing an efficient form of the C approximation
DLPNO-CCSD(T)-F12/D			DLPNO-CCSD(T)-F12 with approach D (less expensive than the C approximation)
DLPNO-CCSD(T1)-F12			DLPNO-CCSD(T1) with F12 correction employing an efficient form of the C approximation
DLPNO-CCSD(T1)-F12/D			DLPNO-CCSD(T1)-F12 with approach D (less expensive than the C approximation)
DLPNO-NEVPT2			DLPNO-NEVPT2 requires a CASSCF block

4.2.1.8. Accuracy control for local correlation methods¶

These keywords select predefined sensible sets of thresholds to control the accuracy of DLPNO calculations. See the corresponding sections on local correlation methods for more details.

Keyword	Input block	Variable	Comment
LoosePNO	MDCI, MP2	Various	Selects loose DLPNO thresholds
NormalPNO			Selects default DLPNO thresholds
TightPNO			Selects tight DLPNO thresholds
DLPNO-HFC1			Tightened truncation setting for DLPNO-CCSD hyperfine coupling constants calculation
DLPNO-HFC2			Tighter truncation setting than for DLPNO-HFC1

4.2.1.9. Automatic basis set extrapolation¶

Keyword	Input block	Variable	Comment
Extrapolate (n/m, bas)			Extrapolation of the basis set family “bas” (bas=cc,aug-cc, cc-core, ano, saug-ano, aug-ano, def2; if omitted “cc-pV$n$Z” is used) for cardinal numbers n,m (n<m=2,3,4,5), e.g. Extrapolate(2/3,cc) extrapolates the SCF, MP2 and MDCI energies to the basis set limit. “core” refers to basis sets with core correlation function. In this case the frozen core approximation is - by default - turned off. This setting can be overridden in the “methods” block if one just wants to use the basis set with core correlation functions (steep primitives) but without unfreezing the core electrons.
Extrapolate (n, bas)			Calculate the first n-energies for member of the basis set family basis, e.g. Extrapolate(3) is doing calculations with cc-pVDZ, cc-pVTZ and cc-pVQZ.
ExtrapolateEP2 (n/m, bas,[method,method-details])			Similar: performs SCF, MP2 and MDCI calculations. The higher basis set can only be done with DLPNO-CCSD(T) or MP2 methods and then used to extrapolate the MDCI calculation to the basis set limit.
ExtrapolateEP3 (bas,[method,method-details])			Similar to EP2: for the high basis set method we go one cardinal number higher.

4.2.1.10. High-level methods for excited states as implemented in the MDCI module¶

An additional block input to define the number of roots is required. The EOM family of methods feature IP and EA extensions. The list below is incomplete as some methods need more refined settings such as the Hilbert space MRCC approaches (MkCCSD/BWCCSD). Note that excited states can also be computed with CIS, RPA, ROCIS and TD-DFT. Please check the excited states section of the manual for details.

Keyword	Input block	Variable	Comment
EOM-CCSD	MDCI	NRoots	Equation of Motion CCSD
bt-PNO-EOM-CCSD			back-transformed PNO approximation
STEOM-CCSD			Similarity Transformed Equation of Motion CCSD
bt-PNO-STEOM-CCSD			back-transformed PNO approximation
STEOM-DLPNO-CCSD			DLPNO approximation
IH-FSMR-CCSD			Fock-Space CCSD using an intermediate Hamiltonian
bt-PNO-IH-FSMR-CCSD			back-transformed PNO approximation

All of them require the CASSCF block as minimal input.

Keyword	Input block	Variable	Comment
DMRG	CASSCF	CIStep	Sets DMRG as “CIStep” in CASSCF
NEVPT2		PTMethod	SC NEVPT2
SC-NEVPT2			SC-NEVPT2 same as NEVPT2
RI-NEVPT2			SC-NEVPT2 with the RI approximation
FIC-NEVPT2			FIC-NEVPT2 aka PC-NEVPT2
DLPNO-NEVPT2			FIC-NEVPT2 in the framework of DLPNO
CASPT2			FIC-CASPT2
RI-CASPT2			FIC-CASPT2 with the RI approximation
DCD-CAS(2)		DCD-CAS	2nd order Dynamic Correlation Dressed CAS
RI-DCD-CAS(2)			2nd order Dynamic Correlation Dressed CAS with RI approximation

4.2.1.12. (internally contracted) Multireference methods beyond NEVPT2/CASPT2¶

If specified in a single keyword all information about reference spaces, number of roots etc. is taken from the CASSCF module that is assumed to be run in advance. These methods reside in the autoci module. More refined settings require the autoci block in the input.

Keyword	Input block	Variable	Comment
FIC-MRCI	AUTOCI	CIType	Invokes the fully internally contracted MRCI
FIC-DDCI3			Fully internally contracted DDCI3
FIC-DDCI3-C0			Fully internally contracted DDCI3-C0
FIC-CEPA(0)			Fully internally contracted CEPA(0)
FIC-ACPF			Fully internally contracted ACPF
FIC-AQCC			Fully internally contracted AQCC
FIC-MRCC			Fully internally contracted MRCCSD

4.2.1.13. (uncontracted) Multireference methods¶

If specified in a single keyword all information about reference spaces, number of roots etc. is taken from the CASSCF module that is assumed to be run in advance. In general, these calculations are of the individually selecting type and are very time consuming. Very many flags can be set and modified for these methods and in general using these methods requires expert users! In general see the variables Tsel, Tpre and Tnat that define the individual selection process. All of these methods can be used with RI integrals by using RI-MRCI etc. However, then the calculations become even more time consuming since integrals are made one- by one on the fly. Non-RI calculations will be pretty much limited to about 200-300 orbitals that are included in the CI.

Keyword	Input block	Variable	Comment
MRCI	MRCI	CIType	Initiates a multireference configuration interaction calculation with single and double excitations
MRCI$+$Q			Same with multireference Davidson correction for unlinked quadruples
MRACPF			Average coupled-pair functional
MRAQCC			Average quadratic coupled-cluster
MRDDCI1			Difference dedicated CI with one degree of freedom
MRDDCI2			Same with two degrees of freedom
MRDDCI3			Same with three degrees of freedom
MRDDCI$n+$Q			MRDDCI with Davidson correction
SORCI			Spectroscopy oriented CI

4.2.1.14. Frozen core features¶

Note

This deviates from previous versions of ORCA! We are now counting core electrons rather than using an energy window. If you do want to use an orbital energy window use %method FrozenCore FC_EWIN end. Otherwise the EWin commands will be ignored! (alternatives are FC_ELECTRONS(default) and FC_NONE).

Keyword	Input block	Variable	Comment
FROZENCORE	METHOD	FrozenCore	Use a frozen core. By default this is done by counting the number of chemical core electrons
NOFROZENCORE			Do not use a frozen core

4.2.1.15. Semiempirical methods¶

Keyword	Input block	Variable	Comment
ZINDO/S			Selects the ZINDO/S method
ZINDO/1			Selects the ZINDO/1 method
ZINDO/2			Selects the ZINDO/2 method
NDDO/1			Selects the NDDO/1 method
NDDO/2			Selects the NDDO/2 method
MNDO			Selects the MNDO method
AM1			Selects the AM1 method
PM3			Selects the PM3 method

4.2.1.16. Algorithmic variations, options, add-ons, modifiers, …¶

Keyword	Input block	Variable	Comment
RHF or RKS	SCF	HFTYP	Selects closed-shell SCF
UHF or UKS			Selects spin unrestricted SCF
ROHF or ROKS			Selects open-shell spin restricted SCF
AllowRHF	METHOD	ALLOWRHF	Allow a RHF calculation even if the system is open-shell (Mult>1). Default is to switch to UHF then
RI	METHOD	RI	Sets RI$=$true to use the RI approximation in DFT calculations. Default to Split-RI-J
NORI			Sets RI$=$false
RIJCOSX	METHOD/ SCF	RI, KMatrix	Sets the flag for the efficient RIJCOSX algorithm (treat the Coulomb term via RI and the Exchange term via seminumerical integration)
RI-JK	METHOD/ SCF	RI, KMatrix	Sets the flag for the efficient RI algorithm for Coulomb and Exchange. Works for SCF (HF/DFT) energies and gradients. Works direct or conventional.
SPLITJ	SCF	JMATRIX	Select the efficient Split-J procedure for the calculation of the Coulomb matrix in non-hybrid DFT (rarely used)
SPLIT-RI-J	SCF	JMATRIX, RI	Select the efficient Split-RI-J procedure for the improved evaluation of the RI-approximation to the Coulomb-matrix
NoSplit-RI-J	SCF	JMATRIX, RI	Turns the Split-RI-J feature off (but does not set the RI flag to false!)
RI-J-XC	SCF	JMATRIX, KMATRIX, RI	Turn on RI for the Coulomb term and the XC terms. This saves time when the XC integration is significant but introduces another basis set incompleteness error. (rarely used)
DIRECT	SCF	SCFMODE	Selects an integral direct calculation
CONV			Selects an integral conventional calculation
NOITER	SCF	MAXITER	Sets the number of SCF iterations to 0. This works together with MOREAD and means that the program will work with the provided starting orbitals.

4.2.1.17. Initial guess options¶

In most cases the default PMODEL guess will be adequate. In some special situations you may want to switch to a different choice.

Keyword	Input block	Variable	Comment
PATOM	SCF	GUESS	Selects the polarized atoms guess
PMODEL			Selects the model potential guess
HUECKEL			Selects the extended Hückel guess
HCORE			Selects the one-electron matrix guess
MOREAD			Read MOs from a previous calulation (use `%moinp "myorbitals.gbw"` in a separate line to specify the GBW file that contains these MOs to be read)
AUTOSTART		AUTOSTART	Try to start from the existing GBW file of the same name as the present one (only for single-point calculations)
NOAUTOSTART			Don’t try to do that

Keyword	Input block	Variable	Comment
DecontractBas	BASIS	DecontractBas	Decontract the basis set. If the basis set arises from general contraction, duplicate primitives will be removed.
NoDecontractBas		NoDecontractBas	Do not decontract the basis set
DecontractAuxJ		DecontractAuxJ	Decontract the AuxJ basis set
NoDecontractAuxJ		NoDecontractAuxJ	Do not decontract the AuxJ basis
DecontractAuxJK		DecontractAuxJK	Decontract the AuxJK basis set
NoDecontractAuxJK		NoDecontractAuxJK	Do not decontract the AuxJK basis
DecontractAuxC		DecontractAuxC	Decontract the AuxC basis set
NoDecontractAuxC		NoDecontractAuxC	Do not decontract the AuxC basis
Decontract		Decontract	Decontract all (orbital and auxiliary) basis sets

4.2.1.19. Relativistic options¶

There are several variants of scalar relativistic Hamiltonians to use in all electron calculations. See Relativistic Options for details.

Keyword	Input block	Variable	Comment
DKH or DKH2	REL	METHOD/ORDER	Selects the scalar relativistic Douglas–Kroll–Hess Hamiltonian of 2nd order
ZORA	REL	METHOD	Selects the scalar relativistic ZORA Hamiltonian
X2C	REL	METHOD	Selects the scalar relativistic X2C Hamiltonian
DLU-X2C	REL	METHOD/DLU	Selects the scalar relativistic X2C Hamiltonian with the diagonal local approximation to the unitary transformation matrix

4.2.1.20. Grid options¶

Keyword	Input block	Variable	Comment
DEFGRID$n$ ($n=1$–3)	METHOD	GRID	Selects the integration grids
NOFINALGRIDX			Turn off the final grid in COSX (not recommended)

4.2.1.21. Convergence thresholds¶

These keywords control how tightly the SCF and geometry optimizations will be converged. The program makes an effort to set the convergence thresholds for correlation modules consistently with that of the SCF.

Keyword	Input block	Variable	Comment
NORMALSCF	SCF	CONVERGENCE	Selects normal SCF convergence
LOOSESCF			Selects loose SCF convergence
SLOPPYSCF			Selects sloppy SCF convergence
STRONGSCF			Selects strong SCF convergence
TIGHTSCF			Selects tight SCF convergence
VERYTIGHTSCF			Selects very tight SCF convergence
EXTREMESCF			Selects “extreme” convergence. All thresholds are practically reduced to numerical precision of the computer. Only for benchmarking (very expensive).
SCFCONV$n$			Selects energy convergence check and sets $ETol$ to $10^{-n}$ ($n=6$–10). Also selects appropriate thresh, tcut, and bfcut values.
VERYTIGHTOPT	GEOM	TolE, TolRMSG	Selects very tight optimization convergence
TIGHTOPT		TolMaxG	Selects tight optimization convergence
NORMALOPT		TolRMSD, TolMaxD	Selects default optimization convergence
LOOSEOPT			Selects loose optimization convergence

4.2.1.22. Convergence acceleration¶

The default is DIIS which is robust. For most closed-shell organic molecules SOSCF converges somewhat better and might be a good idea to use. For “trailing convergence”, KDIIS or the trust-region augmented Hessian procedures TRAH-SCF might be good choices.

Keyword	Input block	Variable	Comment
DIIS	SCF	DIIS	Turns DIIS on
NODIIS			Turns DIIS off
KDIIS	SCF	KDIIS	Turns Kollmar’s DIIS on
TRAH	SCF	TRAH	Turns trust-region augmented Hessian SCF on
NOTRAH			Turns trust-region augmented Hessian SCF off
SOSCF	SCF	SOSCF	Turns SOSCF on
NOSOSCF			Turns SOSCF off
DAMP	SCF	CNVDAMP	Turns damping on
NODAMP			Turns damping off
LSHIFT	SCF	CNVSHIFT	Turns level shifting on
NOLSHIFT			Turns level shifting off

4.2.1.23. Convergence strategies¶

(does not modify the convergence criteria)

Keyword	Input block	Comment
EasyConv		Assumes no convergence problems.
NormalConv		Normal convergence criteria.
SlowConv		Selects appropriate SCF converger criteria for difficult cases. Most transition metal complexes fall into this category.
VerySlowConv		Selects appropriate SCF converger criteria for very difficult cases.
CPCM(solvent)	CPCM	Invoke the conductor-like polarizable continuum model with a standard solvent (see section [sec:solvationmodels.detailed] for a list of solvents). If no solvent is given, infinity (a conductor) is assumed.

4.2.1.24. Spin-orbit coupling¶

Keyword	Input block	Variable	Comment
SOMF(1X)	REL	SOCType, SOCFlags	Invokes the SOMF(1X) treatment of the spin-orbit coupling operator.
RI-SOMF(1X)			Invokes the SOMF(1X) treatment of the spin-orbit coupling operator, with RI for the Coulomb part.
SOMF(4X)	REL	SOCType, SOCFlags	Invokes the SOMF(4X) treatment of the spin-orbit coupling operator.
RI-SOMF(4X)			Invokes the SOMF(4X) treatment of the spin-orbit coupling operator, with RI for the Coulomb part.
SOMF(4XS)	REL	SOCType, SOCFlags	Invokes the SOMF(4XS) treatment of the spin-orbit coupling operator.
RI-SOMF(4XS)			Invokes the SOMF(4XS) treatment of the spin-orbit coupling operator, with RI for the Coulomb part.
VEFF-SOC			Invokes the VEFF-SOC treatment of the spin-orbit coupling operator.
VEFF(-2X)-SOC			Invokes the VEFF(-2X)-SOC treatment of the spin-orbit coupling operator.
AMFI			Invokes the AMFI treatment of the spin-orbit coupling operator.
ZEFF-SOC			Uses effective nuclear charges for the spin-orbit coupling operator.

4.2.1.25. Miscellaneous options¶

Keyword	Input block	Variable	Comment
ANGS	COORDS	UNITS	Select angstrom units
BOHRS			Select input coordinates in atomic units
FRACOCC	SCF	FRACOCC	Turns the fractional occupation option on (FOD is always calculated in this case)
NoPropFile	Method	Method	Turns writing to property file off. By default is on for everything, except MD and L-Opt calculations
SMEAR	SCF	SMEARTEMP	Temperature for occupation number smearing on (default is 5000 K; FOD (see Fractional Occupation Number Weighted Electron Density (FOD)) is always calculated in this case)
NOSMEAR			Turn occupation number smearing off
KEEPINTS	SCF	KEEPINTS	Keep two electron integrals on disk
NOKEEPINTS			Do not keep two electron integrals
KEEPDENS	SCF	KEEPDENS	Keep the density matrix on disk
NOKEEPDENS			Do not keep the density matrix
KEEPTRANSDENSITY		KEEPTRANSDENSITY	Keep the transition density matrices on disk
READINTS	SCF	READINTS	Reading of two electron integrals on
NOREADINTS			Reading of two electron integrals off
CHEAPINTS	SCF	USECHEAPINTS	Use the cheap integral feature in direct SCF calculations
NOCHEAPINTS			Turn that feature off
FLOAT	SCF	VALFORMAT	Set storage format for numbers to single precision (SCF, RI-MP2, CIS, CIS(D), MDCI)
DOUBLE	SCF	VALFORMAT	Set storage format for numbers to double precision (default)
UCFLOAT	SCF	VALFORMAT COMPRESSION	Use float storage in the matrix containers without data compression
CFLOAT	SCF	VALFORMAT COMPRESSION	Use float storage in the matrix containers with data compression
UCDOUBLE	SCF	VALFORMAT COMPRESSION	Use double storage in the matrix containers without data compression
CDOUBLE	SCF	VALFORMAT COMPRESSION	Use double storage in the matrix containers with data compression

4.2.1.26. Output control¶

Keyword	Input block	Variable	Comment
NORMALPRINT	OUTPUT	PRINTLEVEL	Selects the normal output
MINIPRINT			Selects the minimal output
SMALLPRINT			Selects the small output
LARGEPRINT			Selects the large output
PRINTMOS	OUTPUT	Print[p_MOS]	Prints MO coefficients
NOPRINTMOS	OUTPUT		Suppress printing of MO coefficients
PRINTBASIS	OUTPUT	Print[p_basis]	Print the basis set in input format
PRINTGAP	OUTPUT	Print[p _homolumogap]	Prints the HOMO/LUMO gap in each SCF iteration. This may help to detect convergence problems
ALLPOP	OUTPUT	Print[…]	Turns on all population analysis
NOPOP			Turns off all populaton analysis
MULLIKEN			Turns on the Mulliken analysis
NOMULLIKEN			Turns off the Mulliken analysis
LOEWDIN			Turns on the Loewdin analysis
NOLOEWDIN			Turns off the Loewdin analysis
MAYER			Turns on the Mayer analysis
NOMAYER			Turns off the Mayer analysis
NPA			Turns on interface for the NPA analysis using the GENNBO program
NBO			Turns on the interface for the NPA plus NBO analysis with the GENNBO program
NONPA			Turns off NPA analysis
NONBO			Turns of NBO analysis
REDUCEDPOP			Prints Loewdin reduced orb.pop per MO
NOREDUCEDPOP			Turns this feature off
UNO	SCF	UNO	Produce UHF natural orbitals
AIM			Produce a WFN file
XYZFILE	OUTPUT	XYZFILE	Produce an XYZ coordinate file
PDBFILE		PDBFILE	Produce a PDB file

4.2.1.27. Nudged Elastic Band methods¶

Keyword	Input block	Variable	Comment
NEB			Selects standard NEB method
ZOOM-NEB			ZOOM-NEB method
NEB-IDPP			Initial path NEB calculation
NEB-CI			Climbing image NEB calculation
ZOOM-NEB-CI			Zoom version of NEB-CI
NEB-MMFTS			NEB + subsequent MMF-TS optimization
NEB-TS			NEB + subsequent transition state optimization
ZOOM-NEB-TS			ZOOM-NEB + subsequent transition state optimization
FLAT-NEB-TS
FAST-NEB-TS			NEB with one iteration + subsequent transtion state optimization
LOOSE-NEB-TS
TIGHT-NEB-TS			Select tight convergence criteria

4.2.1.28. Compression and storage¶

The data compression and storage options deserve some comment: in a number of modules including RI-MP2, MDCI, CIS, (D) correction to CIS, etc. the program uses so called “Matrix Containers”. This means that the data to be processed is stored in terms of matrices in files and is accessed by a double label. A typical example is the exchange operator K$^{\textbf{ij} }$ with matrix elements $K^{ij}(a,b)=(ia|jb)$. Here the indices $i$ and $j$ refer to occupied orbitals of the reference state and $a$ and $b$ are empty orbitals of the reference state. Data of this kind may become quite large (formally $N^4$ scaling). To store the numbers in single precision cuts down the memory requirements by a factor of two with (usually very) slight loss in precision. For larger systems one may also gain advantages by also compressing the data (e.g. use a “packed” storage format on disk). This option leads to additional packing/unpacking work and adds some overhead. For small molecules UCDOUBLE is probably the best option, while for larger molecules UCFLOAT or particularly CFLOAT may be the best choice. Compression does not necessarily slow the calculation down for larger systems since the total I/O load may be substantially reduced and thus (since CPU is much faster than disk) the work of packing and unpacking takes less time than to read much larger files (the packing may reduce disk requirements for larger systems by approximately a factor of 4 but it has not been extensively tested so far). There are many factors contributing to the overall wall clock time in such cases including the total system load. It may thus require some experimentation to find out with which set of options the program runs fastest with.

Caution

It is possible that FLOAT may lead to unacceptable errors. Thus it is not the recommended option when MP2 or RI-MP2 gradients or relaxed densities are computed. For this reason the default is DOUBLE.
If you have convinced yourself that FLOAT is OK, it may save you a factor of two in both storage and CPU.

4.2.1.29. Global memory use¶

Some ORCA modules (in particular those that perform some kind of wavefunction based correlation calculations) require large scratch arrays. Each module has an independent variable to control the size of these dominant scratch arrays. However, since these modules are never running simultaneously, we provide a global variable MaxCore that assigns a certain amount of scratch memory to all of these modules. Thus:

%MaxCore 4000

sets 4000 MB (= 4 GB) as the limit for these scratch arrays. This limit applies per processing core. Do not be surprised if the program takes more than that – this size only refers to the dominant work areas. Thus, you are well advised to provide a number that is significantly less than your physical memory. Note also that the memory use of the SCF program cannot be controlled: it dynamically allocates all memory that it needs and if it runs out of physical memory you are out of luck. This, however, rarely happens unless you run on a really small memory computer or you are running a gigantic job.

4.2.2. Density Functional Methods¶

For density functional calculations a number of standard functionals can be selected via the “simple input” feature. Since any of these keywords will select a DFT method, the keyword “DFT” is not needed in the input. Further functionals are available via the %method block. References are given in Section [sec:model.dft.functionals.detailed]

4.2.2.1. Local and gradient corrected functionals¶

HFS	Hartree–Fock–Slater Exchange only functional
LDA or LSD	Local density approximation (defaults to VWN5)
VWN or VWN5	Vosko-Wilk-Nusair local density approx. parameter set “V”
VWN3	Vosko-Wilk-Nusair local density approx. parameter set “III”
PWLDA	Perdew-Wang parameterization of LDA
BP86 or BP	Becke ‘88 exchange and Perdew ‘86 correlation
BLYP	Becke ‘88 exchange and Lee-Yang-Parr correlation
OLYP	Handy’s “optimal” exchange and Lee-Yang-Parr correlation
GLYP	Gill’s ‘96 exchange and Lee-Yang-Parr correlation
XLYP	The Xu and Goddard exchange and Lee-Yang-Parr correlation
PW91	Perdew-Wang ‘91 GGA functional
mPWPW	Modified PW exchange and PW correlation
mPWLYP	Modified PW exchange and LYP correlation
PBE	Perdew-Burke-Erzerhoff GGA functional
RPBE	“Modified” PBE
REVPBE	“Revised” PBE
RPW86PBE	PBE correlation with refitted Perdew ‘86 exchange
PWP	Perdew-Wang ‘91 exchange and Perdew ‘86 correlation

4.2.2.2. Hybrid functionals¶

B1LYP	The one-parameter hybrid functional with Becke ‘88 exchange and Lee-Yang-Parr correlation (25% HF exchange)
B3LYP and B3LYP/G	The popular B3LYP functional (20% HF exchange) as defined in the TurboMole program system and the Gaussian program system, respectively
O3LYP	The Handy hybrid functional
X3LYP	The Xu and Goddard hybrid functional
B1P	The one-parameter hybrid version of BP86
B3P	The three-parameter hybrid version of BP86
B3PW	The three-parameter hybrid version of PW91
PW1PW	One-parameter hybrid version of PW91
mPW1PW	One-parameter hybrid version of mPWPW
mPW1LYP	One-parameter hybrid version of mPWLYP
PBE0	One-parameter hybrid version of PBE
REVPBE0	“Revised” PBE0
REVPBE38	“Revised” PBE0 with 37.5% HF exchange
BHANDHLYP	Half-and-half hybrid functional by Becke

4.2.2.3. Meta-GGA and hybrid meta-GGA functionals¶

TPSS	The TPSS meta-GGA functional
TPSSh	The hybrid version of TPSS (10% HF exchange)
TPSS0	A 25% exchange version of TPSSh that yields improved energetics
M06L	The Minnesota M06-L meta-GGA functional
M06	The M06 hybrid meta-GGA (27% HF exchange)
M062X	The M06-2X version with 54% HF exchange
PW6B95	Hybrid functional by Truhlar
B97M-V	Head-Gordon’s DF B97M-V with VV10 nonlocal correlation
B97M-D3BJ	Modified version of B97M-V with D3BJ correction by Najibi and Goerigk
B97M-D4	Modified version of B97M-V with DFT-D4 correction by Najibi and Goerigk
SCANfunc	Perdew’s SCAN functional
r2SCAN	Regularized and restored SCAN functional by Furness, Sun et. al.
r2SCANh	Global hybrid variant of $r^2$ SCAN with 10% HF exchange
r2SCAN0	Global hybrid variant of $r^2$ SCAN with 25% HF exchange
r2SCAN50	Global hybrid variant of $r^2$ SCAN with 50% HF exchange

4.2.2.4. Range-separated hybrid functionals¶

wB97	Head-Gordon’s fully variable DF $\omega$B97
wB97X	Head-Gordon’s DF $\omega$B97X with minimal Fock exchange
wB97X-D3	Chai’s refit incl. D3 in its zero-damping version
wB97X-D4	Modified version of $\omega$B97X-V with DFT-D4 correction by Najibi and Goerigk
wB97X-D4rev	Modified version of $\omega$B97X-V with DFT-D4 correction by Grimme et al.
wB97X-V	Head-Gordon’s DF $\omega$B97X-V with VV10 nonlocal correlation
wB97X-D3BJ	Modified version of $\omega$B97X-V with D3BJ correction by Najibi and Goerigk
wB97M-V	Head-Gordon’s DF $\omega$B97M-V with VV10 nonlocal correlation
wB97M-D3BJ	Modified version of $\omega$B97M-V with D3BJ correction by Najibi and Goerigk
wB97M-D4	Modified version of $\omega$B97M-V with DFT-D4 correction by Najibi and Goerigk
wB97M-D4rev	Modified version of $\omega$B97M-V with DFT-D4 correction by Grimme et al.
CAM-B3LYP	Handy’s fit
LC-BLYP	Hirao’s original application
LC-PBE	range-separated PBE-based hybrid functional with 100% Fock exchange in the long-range regime
wr2SCAN	Range-separated hybrid variant of $r^2$ SCAN with 0-100% HF exchange

4.2.2.5. Perturbatively corrected double-hybrid functionals¶

Add the prefix RI- or DLPNO- to use the respective approximation for the MP2 part.

B2PLYP	Grimme’s mixture of B88, LYP, and MP2
mPW2PLYP	mPW exchange instead of B88, which is supposed to improve on weak interactions.
B2GP-PLYP	Gershom Martin’s “general purpose” reparameterization
B2K-PLYP	Gershom Martin’s “kinetic” reparameterization
B2T-PLYP	Gershom Martin’s “thermochemistry” reparameterization
PWPB95	Goerigk and Grimme’s mixture of modified PW91, modified B95, and SOS-MP2
PBE-QIDH	Adamo and co-workers’ “quadratic integrand” double hybrid with PBE exchange and correlation
PBE0-DH	Adamo and co-workers’ PBE-based double hybrid
DSD-BLYP	Gershom Martin’s “general purpose” double-hybrid with B88 exchange, LYP correlation and SCS-MP2 mixing, i.e. not incl. D3BJ correction
DSD-PBEP86	Gershom Martin’s “general purpose” double-hybrid with PBE exchange, P86 correlation and SCS-MP2 mixing, i.e. not incl. D3BJ correction
DSD-PBEB95	Gershom Martin’s “general purpose” double-hybrid with PBE exchange, B95 correlation and SCS-MP2 mixing, i.e. not incl. D3BJ correction
revDSD-PBEP86/2021, revDSD-PBEP86-D4/2021	Double-Hybrid Functional with with PBE exchange, B95 correlation and SCS-MP2 Mixing
revDOD-PBEP86/2021, revDOD-PBEP86-D4/2021	Double-Hybrid Functional with with PBE exchange, B95 correlation and SOS-MP2 Mixing
Pr2SCAN50	Global SOS-double-hybrid variant of $r^2$ SCAN with 50% HF exchange
Pr2SCAN69	Global SOS-double-hybrid variant of $r^2$ SCAN with 69% HF exchange
kPr2SCAN50	Global SOS-double-hybrid variant of $r^2$ SCAN with 50% HF exchange and kappa-regularized MP2

4.2.2.6. Range-separated double-hybrid functionals¶

Add the prefix RI- or DLPNO- to use the respective approximation for the MP2 part.

wB2PLYP	Goerigk and Casanova-Páez’s range-separated DHDF, with the correlation contributions based on B2PLYP, optimized for excitation energies
wB2GP-PLYP	Goerigk and Casanova-Páez’s range-separated DHDF, with the correlation contributions based on B2GP-PLYP, optimized for excitation energies
RSX-QIDH	range-separated version of the PBE-QIDH double-hybrid by Adamo and co-workers
RSX-0DH	range-separated version of the PBE-0DH double-hybrid by Adamo and co-workers
wB88PP86	Casanova-Páez and Goerigk’s range-separated DHDF based on Becke88 exchange and P86 correlation, optimized for excitation energies
wPBEPP86	Casanova-Páez and Goerigk’s range-separated DHDF based on PBE exchange and P86 correlation, optimized for excitation energies
wB97M(2)	Mardirossian and Head-Gordon’s $\omega$B97M(2) range-separated meta-GGA DHDF including VV10 non-local correlation: must be used with $\omega$B97M-V orbitals! See DFT Calculations with Second Order Perturbative Correction (Double-Hybrid Functionals).
wPr2SCAN50	Range-separated SOS-double-hybrid variant of $r^2$ SCAN with 50-100% HF exchange

4.2.2.7. Global and range-separated double-hybrid functionals with spin-component and spin-opposite scaling¶

Add the prefix RI- or DLPNO- to use the respective approximation for the MP2 part.

wB97X-2	Chai and Head-Gordon’s $\omega$B97X-2(TQZ) range-separated GGA-based DHDF with spin-component scaling
SCS/SOS-B2PLYP21	spin-opposite scaled version of B2PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS fit gave SOS version; SOS only applies to the CIS(D) component)
SCS-PBE-QIDH	spin-component scaled version of PBE-QIDH optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-PBE-QIDH	spin-opposite scaled version of PBE-QIDH optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-B2GP-PLYP21	spin-component scaled version of B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-B2GP-PLYP21	spin-opposite scaled version of B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS/SOS-wB2PLYP	spin-opposite scaled version of $\omega$B2PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS fit gave SOS version; SOS only applies to the CIS(D) component)
SCS-wB2GP-PLYP	spin-component scaled version of $\omega$B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wB2GP-PLYP	spin-opposite scaled version of $\omega$B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-RSX-QIDH	spin-component scaled version of RSX-QIDH optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-RSX-QIDH	spin-opposite scaled version of RSX-QIDH optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-wB88PP86	spin-component scaled version of $\omega$B88PPBE86 optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wB88PP86	spin-opposite scaled version of $\omega$B88PPBE86 optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-wPBEPP86	spin-component scaled version of $\omega$PBEPPBE86 optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wPBEPP86	spin-opposite scaled version of $\omega$PBEPPBE86 optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)

4.2.2.8. Composite Methods¶

HF-3c	HF-based composite method by Grimme et al. emplyoing the MINIX basis set
B97-3c	GGA composite method by Grimme et al. employing a modified def2-mTZVP basis set
R2SCAN-3c	meta-GGA composite method by Grimme et al. employing a modified def2-mTZVPP basis set
PBEh-3c	Hybrid (42% HF exchange) composite method by Grimme et al. employing a modified def2-mSVP basis set
wB97X-3c	Range-separated hybrid composite DFT method by Grimme et al. employing a polarized valence double-$\zeta$ basis set

4.2.2.9. Dispersion corrections¶

See DFT Calculations with Atom-pairwise Dispersion Correction and Treatment of Dispersion Interactions with DFT-D3 for details.

D4	density dependent atom-pairwise dispersion correction with Becke-Johnson damping and ATM
D3BJ	Atom-pairwise dispersion correction to the DFT energy with Becke-Johnson damping
D3ZERO	Atom-pairwise dispersion correction with zero damping
D2	Empirical dispersion correction from 2006 (not recommended)

4.2.2.10. Non-local correlation¶

See DFT Calculations with the Non-Local, Density Dependent Dispersion Correction (VV10): DFT-NL for details.

NL	Does a post-SCF correction on the energy only
SCNL	Fully self-consistent approach, adding the VV10 correlation to the KS Hamiltonian

4.3. Basis Sets¶

4.3.1. Standard basis set library¶

There are standard basis sets that can be specified via the “simple input” feature in the keyword line. However, any basis set that is not already included in the ORCA library can be provided either directly in the input or through an external file. See the BASIS input block for a full list of internal basis sets and various advanced aspects (section Choice of Basis Set). Effective core potentials and their use are described in section Effective Core Potentials.

4.3.1.1. Pople-style basis sets¶

STO-3G	Minimal basis set(H–I)
3-21G	Pople 3-21G (H–Cs)
3-21GSP	Buenker 3-21GSP (H–Ar)
4-22GSP	Buenker 4-22GSP (H–Ar)
6-31G	Pople 6-31G and its modifications (H–Zn)
m6-31G	Modified 6-31G for 3d transition metals (Sc–Cu)
6-311G	Pople 6-311G and its modifications (H–Br)

Polarization functions for the 6-31G basis set:

* or (d)	One set of first polarization functions on all atoms except H
** or (d,p)	One set of first polarization functions on all atoms
Further combinations:	(2d), (2df), (2d,p), (2d,2p), (2df,2p), (2df,2pd)

Polarization functions for the 6-311G basis set: All of the above plus (3df) and (3df,3pd)

Diffuse functions for the 6-31G and 6-311G basis sets:

$+$ before “G”	Include diffuse functions on all atoms except H (e.g. 6-31$+$G)
$++$ before “G”	Include diffuse functions on all atoms. Works only when H polarization is already included, e.g. 6-31$++$G(d,p)

4.3.1.2. The def2 basis sets of the Karlsruhe group¶

These basis sets are all-electron for elements H-Kr, and automatically load Stuttgart-Dresden effective core potentials for elements Rb-Rn.

def2-SVP	Valence double-zeta basis set with “new” polarization functions.
def2-SV(P)	The above with slightly reduced polarization.
def2-TZVP	Valence triple-zeta basis set with “new” polarization functions. Note that this is quite similar to the older (“def”) TZVPP for the main group elements and TZVP for hydrogen.
def2-TZVP(-f)	TZVP with f polarization removed from main group elements.
def2-TZVPP	TZVPP basis set with “new” polarization functions.
def2-QZVP	Polarized quadruple-zeta basis.
def2-QZVPP	Accurate doubly polarized quadruple-zeta basis.

4.3.1.3. Older (“def”) Ahlrichs basis sets¶

ECP basis sets for elements Fr-Lr. This basis set automatically employs the original def-ECP.

def-TZVP	Valence triple-zeta basis set with polarization functions.
ma-def-TZVP	Minimally augmented def-TZVP variant with diffuse s and p functions according to Truhlar[918].

All-electron basis sets for elements H-Kr:

SV	Valence double-zeta basis set.
SV(P)	Valence double-zeta with polarization only on heavy elements.
SVP	Polarized valence double-zeta basis set.
TZV	Valence triple-zeta basis set.
TZV(P)	Valence triple-zeta with polarization on heavy elements.
TZVP	Polarized valence triple-zeta basis set.
TZVPP	Doubly polarized triple-zeta basis set.
QZVP	Polarized valence quadruple-zeta basis set.
QZVPP	Doubly polarized quadruple-zeta basis set.

Note

Past versions of ORCA used to load all-electron basis sets also for elements Rb-I with the above keywords for double- and triple-zeta basis sets. The Rb-I basis sets originated from non-relativistic all-electron basis sets of the Turbomole library (such as “TZVPAlls”). This automatic substitution is now deprecated. However, we offer temporarily the ability to reproduce that behavior by adding the prefix “old-” to the above keywords, e.g. old-TZVP.

4.3.1.4. Diffuse def2 basis sets¶

Minimally augmented def2 basis sets:	Augmented def2 basis sets by diffuse s and p functions according to Truhlar[918]. Recommended for general use.
ma-def2-SVP	Minimally augmented def2-SVP basis set.
ma-def2-SV(P)	Minimally augmented def2-SV(P) basis set.
ma-def2-TZVP	Minimally augmented def2-TZVP basis set.
ma-def2-TZVP(-f)	Minimally augmented def2-TZVP(-f) basis set.
ma-def2-TZVPP	Minimally augmented def2-TZVPP basis set.
ma-def2-QZVPP	Minimally augmented def2-QZVPP basis set.

Rappoport property-optimized diffuse def2 basis sets:	Augmented def2 basis sets by diffuse functions according to Rappoport et al.[710, 711]
def2-SVPD	Diffuse def2-SVP basis set for property calculations
def2-TZVPD	Diffuse def2-TZVP basis set for property calculations
def2-TZVPPD	Diffuse def2-TZVPP basis set for property calculations
def2-QZVPD	Diffuse def2-QZVP basis set for property calculations
def2-QZVPPD	Diffuse def2-QZVPP basis set for property calculations

4.3.1.5. Karlsruhe basis sets with Dirac–Fock ECPs¶

These basis sets are derived from the def2-XVP ones with small modifications for 5s, 6s, 4d, and 5d elements and iodine.[884] They are optimized for the revised Dirac-Fock ECPs (dhf-ECP) as opposed to the Wood–Boring ones (def2-ECP). Versions for two-component methods are also available, e.g. dhf-TZVP-2c, however, such methods are currently not implemented in ORCA.

dhf-SV(P)	based on def2-SV(P)
dhf-SVP	based on def2-SVP
dhf-TZVP	based on def2-TZVP
dhf-TZVPP	based on def2-TZVPP
dhf-QZVP	based on def2-QZVP
dhf-QZVPP	based on def2-QZVPP

4.3.1.6. Relativistically recontracted Karlsruhe basis sets¶

For use in DKH or ZORA calculations we provide adapted versions of the def2 basis sets for the elements H-Kr (i.e., for the all-electron def2 basis sets). These basis sets retain the original def2 exponents but have only one contracted function per angular momentum (and hence are somewhat larger), with contraction coefficients suitable for the respective scalar relativistic Hamiltonian. These basis sets can be called with the prefix DKH- or ZORA-, and can be combined with the SARC basis sets for the heavier elements.

DKH-def2-SVP and ZORA-def2-SVP

DKH-def2-SV(P) and ZORA-def2-SV(P)

DKH-def2-TZVP and ZORA-def2-TZVP

DKH-def2-TZVP(-f) and ZORA-def2-TZVP(-f)

DKH-def2-TZVPP and ZORA-def2-TZVPP

DKH-def2-QZVPP and ZORA-def2-QZVPP

Minimally augmented versions:

ma-DKH-def2-SVP and ma-ZORA-def2-SVP

ma-DKH-def2-SV(P) and ma-ZORA-def2-SV(P)

ma-DKH-def2-TZVP and ma-ZORA-def2-TZVP

ma-DKH-def2-TZVP(-f) and ma-ZORA-def2-TZVP(-f)

ma-DKH-def2-TZVPP and ma-ZORA-def2-TZVPP

ma-DKH-def2-QZVPP and ma-ZORA-def2-QZVPP

The same functionality is offered for the “def” basis sets, e.g. “ZORA-TZVP”. In this case too, the relativistically recontracted versions refer to the elements H-Kr. To replicate the behavior of past ORCA versions for elements Rb-I, the prefix “old-” can be used with these keywords as in the non-relativistic case.

Warning

Previous verions of ORCA made extensive use of automatic basis set substitution and aliasing when the use of the DKH or ZORA Hamiltonians was detected. This is no longer the case! Relativistic versions of Karlsruhe basis sets now have to be requested explicitly with the appropriate prefix. SARC basis sets also have to be requested explicitly

All-electron Karlsruhe basis sets up to Rn for the exact two-component (X2C) Hamiltonian.[690] The “-s” variants, e.g. “def2-TZVPall-s”, are augmented with additional tight functions for NMR shielding calculations.[275] The “-2c” variants, e.g. “def2-TZVPall-2c”, are intended for two-component calculations including spin-orbit coupling (Note that two-component calculations are not implemented in ORCA).

x2c-SV(P)all	2c version: x2c-SV(P)all-2c, NMR version: x2c-SV(P)all-s
x2c-SVPall	2c version: x2c-SVPall-2c, NMR version: x2c-SVPall-s
x2c-TZVPall	2c version: x2c-TZVPall-2c, NMR version: x2c-TZVPall-s
x2c-TZVPPall	2c version: x2c-TZVPPall-2c, NMR version: x2c-TZVPPall-s
x2c-QZVPall	2c version: x2c-QZVPall-2c, NMR version: x2c-QZVPall-s
x2c-QZVPPall	2c version: x2c-QZVPPall-2c, NMR version: x2c-QZVPPall-s

4.3.1.7. SARC basis sets¶

[62, 641, 642, 643, 644, 729]

Segmented all-electron relativistically contracted basis sets for use with the DKH2 and ZORA Hamiltonians. Available for elements beyond Krypton.

SARC-DKH-TZVP

SARC-DKH-TZVPP

SARC-ZORA-TZVP

SARC-ZORA-TZVPP

Note

SARC/J is the general-purpose Coulomb-fitting auxiliary for all SARC orbital basis sets.

4.3.1.8. SARC2 basis sets for the lanthanides¶

[52]

SARC basis sets of valence quadruple-zeta quality for lanthanides, with NEVPT2-optimized (3g2h) polarization functions. Suitable for accurate calculations using correlated wavefunction methods.

SARC2-DKH-QZVP

SARC2-ZORA-QZVP

Note

Can be called without the polarization functions using …-QZV. Each basis set has a large dedicated /JK auxiliary basis set for simultaneous Coulomb and exchange fitting.

4.3.1.9. Jensen basis sets¶

pc-$n$	($n=$ 0, 1, 2, 3, 4) “Polarization-consistent” generally contracted basis sets (H–Kr) of up to quintuple-zeta quality, optimized for SCF calculations
aug-pc-$n$	As above, augmented by diffuse functions
pcseg-$n$	Segmented PC basis sets (H–Kr), DFT-optimized
aug-pcseg-$n$	As above, augmented by diffuse functions
pcSseg-$n$	Segmented contracted basis sets (H–Kr) optimized for nuclear magnetic shielding
aug-pcSseg-$n$	As above, augmented by diffuse functions
pcJ-$n$	Segmented contracted basis sets (H–Ar) optimized for spin-spin coupling constants
aug-pcJ-$n$	As above, augmented by diffuse functions

4.3.1.10. Lehtolas hydrogenic Gaussian basis sets¶

[505]

HGBS-$m$	($m=$ 5, 7, 9) Lehtolas hydrogenic Gaussian basis sets optimized to the energy threshold $m$ (H-Og)
HGBSP$n$-$m$	($n=$ 1, 2, 3; $m=$ 5, 7, 9) Variants with $n$ polarization shells

Augmented versions:

AHGBS-$m$	($m=$ 5, 7, 9) Variants augmented by diffuse functions
AHGBSP$n$-$m$	($n=$ 1, 2, 3; $m=$ 5, 7, 9)

4.3.1.11. Sapporo basis sets¶

Sapporo-$n$ZP-2012	($n=$ D, T, Q) All-electron generally contracted non-relativistic basis sets (H–Xe)
Sapporo-DKH3-$n$ZP-2012	($n=$ D, T, Q) All-electron basis sets optimized for the DKH3 Hamiltonian and finite nucleus (K–Rn)

4.3.1.12. Correlation-consistent basis sets¶

cc-pVDZ	Dunning correlation-consistent polarized double-zeta
cc-pVTZ	Dunning correlation-consistent polarized triple-zeta
cc-pVQZ	Dunning correlation-consistent polarized quadruple-zeta
cc-pV5Z	Dunning correlation-consistent polarized quintuple-zeta
cc-pV6Z	Dunning correlation-consistent polarized sextuple-zeta
aug-cc-pV$n$Z	($n=$ D, T, Q, 5, 6) Augmented with diffuse functions
cc-pCV$n$Z	($n=$ D, T, Q, 5, 6) Core-polarized basis sets
aug-cc-pCV$n$Z	($n=$ D, T, Q, 5, 6) as above, augmented with diffuse functions
cc-pwCV$n$Z	($n=$ D, T, Q, 5) Core-polarized with weighted core functions
aug-cc-pwCV$n$Z	($n=$ D, T, Q, 5) as above, augmented with diffuse functions
cc-pV$n$(+d)Z	($n=$ D, T, Q, 5) with tight d functions

4.3.1.13. Partially augmented correlation-consistent basis sets¶

[646]

apr-cc-pV(Q+d)Z	Augmented with sp diffuse functions on Li–Ca
may-cc-pV($n$+d)Z	($n=$ T, Q): sp (T), spd (Q) on Li–Ca
jun-cc-pV($n$+d)Z	($n=$ D, T, Q): sp (D), spd (T), spdf (Q) on Li–Ca
jul-cc-pV($n$+d)Z	($n=$ D, T, Q): spd (D), spdf (T), spdfg (Q) on Li–Ca
maug-cc-pV($n$+d)Z	same as jun-, may-, and apr- for $n=$ D, T, and Q, respectively

4.3.1.14. DKH versions of correlation-consistent basis sets¶

cc-pV$n$Z-DK	($n=$ D, T, Q, 5) Correlation-consistent all-electron basis sets for use with the 2nd-order Douglas-Kroll-Hess Hamiltonian
aug-cc-pV$n$Z-DK	($n=$ D, T, Q, 5) as above, augmented with diffuse functions
cc-pwCV$n$Z-DK	($n=$ D, T, Q, 5) DK versions of weighted core correlation-consistent basis sets
aug-cc-pwCV$n$Z-DK	($n=$ D, T, Q, 5) weighted-core DK basis sets with diffuse functions
cc-pV$n$Z-DK3	($n=$ D, T, Q) Correlation-consistent all-electron basis sets for lanthanides and actinides with the 3rd-order Douglas-Kroll-Hess Hamiltonian
cc-pwCV$n$Z-DK3	($n=$ D, T, Q) DK versions of weighted core correlation-consistent basis sets for lanthanides and actinides

4.3.1.15. ECP-based versions of correlation-consistent basis sets¶

cc-pV$n$Z-PP	($n=$ D, T, Q, 5) Correlation-consistent basis sets combined with SK-MCDHF-RSC effective core potentials
aug-cc-pV$n$Z-PP	($n=$ D, T, Q, 5) as above, augmented with diffuse functions
cc-pwCV$n$Z-PP	($n=$ D, T, Q, 5) with weighted core functions
aug-cc-pwCV$n$Z-PP	($n=$ D, T, Q, 5) as above, augmented with diffuse functions

4.3.1.16. F12 and F12-CABS basis sets¶

cc-pV$n$Z-F12	($n=$ D, T, Q) Special orbital basis sets for F12 calculations (larger than the regular D, T, Q-zeta basis sets!)
cc-pCV$n$Z-F12	($n=$ D, T, Q) with core polarization functions
cc-pV$n$Z-PP-F12	($n=$ D, T, Q) ECP-based versions
cc-pV$n$Z-F12-CABS	($n=$ D, T, Q) Near-complete auxiliary basis sets for F12 calculations
cc-pV$n$Z-F12-OptRI	($n=$ D, T, Q) identical to the cc-pV$n$Z-F12-CABS basis above
cc-pCV$n$Z-F12-OptRI	($n=$ D, T, Q)
cc-pV$n$Z-PP-F12-OptRI	($n=$ D, T, Q)
aug-cc-pV$n$Z-PP-OptRI	($n=$ D, T, Q, 5)
aug-cc-pwCV$n$Z-PP-OptRI	($n=$ D, T, Q, 5)

4.3.1.17. Atomic Natural Orbital basis sets¶

ANO-pV$n$Z	($n=$ D, T, Q, 5, 6). Our newly contracted ANO basis sets on the basis of the cc-pV6Z (or pc-4 where missing) primitives. These are very accurate basis sets that are significantly better than the cc-pV$n$Z counterparts for the same number of basis functions (but much larger number of primitives of course).
saug-ANO-pV$n$Z	($n=$ D, T, Q, 5) augmentation with a single set of sp functions. Greatly enhances the accuracy of the SCF energies but not for correlation energies.
aug-ANO-pV$n$Z	($n=$ D, T, Q, 5) full augmentation with spd, spdf, spdfg set of polarization functions. Almost as expensive as the next higher basis set. In fact, aug-ANO-pV$n$Z $=$ ANO-pV($n+1$)Z with the highest angular momentum polarization function deleted.

Relativistic contracted ANO-RCC basis sets:

ANO-RCC-FULL	The complete ANO-RCC basis sets (H-Cm). Some default contractions are provided for convenience with the keywords:
ANO-RCC-DZP
ANO-RCC-TZP
ANO-RCC-QZP

4.3.1.18. Miscellaneous and specialized basis sets¶

D95	Dunning’s double-zeta basis set (H–Cl).
D95p	Polarized version of D95.
MINI	Huzinaga’s minimal basis set.
MINIS	Scaled version of the MINI.
MIDI	Huzinaga’s valence double-zeta basis set.
MINIX	Combination of small basis sets by Grimme (see Table Table 7.7).
vDZP	Molecule-optimized polarized valence double-$\zeta$ basis set by Grimme et al. designed for $\omega$B97X-3c[540].
Wachters+f	First-row transition metal basis set (Sc–Cu).
Partridge-$n$	($n=$ 1, 2, 3, 4) Uncontracted basis sets by Partridge.

LANL2DZ	Los Alamos valence double-zeta with Hay–Wadt ECPs.
LANL2TZ	Triple-zeta version.
LANL2TZ(f)	Triple-zeta plus polarization.
LANL08	Uncontracted basis set.
LANL08(f)	Uncontracted basis set + polarization.

EPR-II	Barone’s basis set (H, B–F) for EPR calculations (double-zeta).
EPR-III	Barone’s basis set for EPR calculations (triple-zeta).
IGLO-II	Kutzelnigg’s basis set (H, B-F, Al–Cl) for NMR and EPR calculations.
IGLO-III	Larger version of the above.
aug-cc-pVTZ-J	Sauer’s basis set for accurate hyperfine coupling constants.

4.3.2. Auxiliary basis sets¶

Auxiliary basis sets for the RI-J and RI-MP2 approximations can also be specified directly in the simple input:

4.3.2.1. Auxiliary basis sets for Coulomb fitting¶

Def/J	Weigend’s “universal” Coulomb fitting basis that is suitable for all def type basis sets. Assumes the use of ECPs beyond Kr (do not use with DKH/ZORA).
Def2/J	Weigend’s “universal” Coulomb fitting basis that is suitable for all def2 type basis sets. Assumes the use of ECPs beyond Kr (do not use with DKH/ZORA).
SARC/J	General-purpose Coulomb fitting basis set for all-electron calculations. Consists of the decontracted def2/J up to Kr and of our own auxiliary basis sets for the rest of the periodic table. Appropriate for use in DKH or ZORA calculations with the recontracted versions of the all-electron def2 basis sets (up to Kr) and the SARC basis sets for the heavier elements.
x2c/J	Weigend’s Coulomb fitting basis for the all-electron x2c-XVPall basis sets.

4.3.2.2. Auxiliary basis sets for simultaneously fitting Coulomb and exchange¶

Fitting basis sets developed by Weigend for fitting simultaneously Coulomb and exchange energies. They are quite large and accurate. They fit SCF energies very well but even if they are large they do not fit correlation as well as the dedicated “/C” auxiliary basis sets.

Def2/JK	Coulomb$+$Exchange fitting for all def2 basis sets
Def2/JKsmall	reduced version of the above
cc-pV$n$Z/JK	($n=$ T, Q, 5) for the respective cc-pV$n$Z orbital basis
aug-cc-pV$n$Z/JK	($n=$ T, Q, 5) for the respective aug-cc-pV$n$Z orbital basis

4.3.2.3. Auxiliary basis sets for correlation calculations¶

Def2-SVP/C	Correlation fitting for the def2-SVP orbital basis
Def2-TZVP/C	for the def2-TZVP orbital basis
Def2-TZVPP/C	for the def2-TZVPP orbital basis
Def2-QZVPP/C	for the def2-QZVPP orbital basis
Def2-SVPD/C	for the def2-SVPD orbital basis
Def2-TZVPD/C	for the def2-TZVPD orbital basis
Def2-TZVPPD/C	for the def2-TZVPPD orbital basis
Def2-QZVPPD/C	for the def2-QZVPPD orbital basis
cc-pV$n$Z/C	($n=$ D, T, Q, 5, 6) for the respective cc-pV$n$Z orbital basis
aug-cc-pV$n$Z/C	($n=$ D, T, Q, 5, 6) for the respective aug-cc-pV$n$Z orbital basis
cc-pwCV$n$Z/C	($n=$ D, T, Q, 5) for the respective cc-pwCV$n$Z orbital basis
aug-cc-pwCV$n$Z/C	($n=$ D, T, Q, 5) for the respective aug-cc-pwCV$n$Z orbital basis
cc-pV$n$Z-PP/C	($n=$ D, T, Q) for the respective cc-pV$n$Z-PP orbital basis
aug-cc-pV$n$Z-PP/C	($n=$ D, T, Q) for the respective aug-cc-pV$n$Z-PP orbital basis
cc-pwCV$n$Z-PP/C	($n=$ D, T, Q) for the respective cc-pwCV$n$Z-PP orbital basis
aug-cc-pwCV$n$Z-PP/C	($n=$ D, T, Q) for the respective aug-cc-pwCV$n$Z-PP orbital basis
cc-pV$n$Z-F12-MP2fit	($n=$ D, T, Q) for the respective cc-pV$n$Z-F12 orbital basis
cc-pCV$n$Z-F12-MP2fit	($n=$ D, T, Q) for the respective cc-pCV$n$Z-F12 orbital basis
cc-pV$n$Z-PP-F12-MP2fit	($n=$ D, T, Q) for the respective cc-pV$n$Z-PP-F12 orbital basis
AutoAux	Automatic construction of a general purpose auxiliary basis for simultaneously fitting Coulomb, exchange and correlation calculations. See section Automatic generation of auxiliary basis sets for details.

Note

ORCA versions before 4.0 allowed the use of multiple keywords to invoke the same def2 Coulomb or Coulomb+exchange fitting basis set of Weigend. To avoid confusion all these keywords are now deprecated and the auxiliary basis sets are simply called using “def2/J” and “def2/JK”.

Note

Starting from version 4.1 ORCA internally stores up to five basis sets for each calculation: the obligatory orbital basis set; an AuxJ Coulomb-fitting basis for the RI-J, RIJDX/RIJONX, and RIJCOSX approximations; an AuxJK Coulomb- and exchange-fitting basis used for RIJK; an AuxC auxiliary basis for the RI approximation in dynamical electron correlation treatments (such as RI-MP2, RI-CCSD, and DLPNO methods); and a complementary auxiliary basis set (CABS) for F12 methods. “/J” basis sets given in the simple input are assigned to AuxJ and likewise for the other types. Non-standard assignments like AuxJ="def2/JK" are possible only through the %basis block input (see section Built-in Basis Sets).

4.3.3. Use of scalar relativistic basis sets¶

For DKH and ZORA calculations ORCA provides relativistically recontracted versions of the Karlsruhe basis sets for elements up to Kr. These can be requested by adding the prefix DKH- or ZORA- to the normal basis set name. Note that for other non-relativistic basis sets (for example Pople-style bases) no recontraction has been performed and consequently such calculations are inconsistent! The basis set and the scalar relativistic Hamiltonian are specified in the keyword line, for example:

! B3LYP ZORA ZORA-TZVP  ...

If an auxiliary basis set is required for these recontracted Karlsruhe basis sets, we recommend the use of the decontracted def2/J. This can be obtained simply by using the keyword “! SARC/J” (instead of the equivalent “! def2/J DecontractAuxJ”) and is the recommended option as it simultaneously covers the use of SARC basis sets for elements beyond Krypton.

! TPSS ZORA ZORA-def2-TZVP SARC/J  ...

For all-electron calculations with elements heavier than Krypton we offer the SARC (segmented all-electron relativistically contracted) basis sets [62, 641, 642, 643, 644, 729]. These were specifically developed for scalar relativistic calculations and are individually adapted to the DKH2 and ZORA Hamiltonians. In this case the Coulomb-fitting auxiliary basis set must be specified as SARC/J, or alternatively the AutoAux keyword (Automatic generation of auxiliary basis sets) can be employed to create auxiliary basis sets.

! PBE DKH SARC-DKH-TZVP SARC/J  ...

Specifically for wavefunction-based calculations of lanthanide systems we recommend the more heavily polarized SARC2 basis sets [52].

Other basis sets suitable for scalar relativistic calculations are various versions of the all-electron correlation-consistent basis sets that are optimized for the DKH2 Hamiltonian and can be called with the suffix “-DK”. The relativistically contracted atomic natural orbital (ANO-RCC) basis sets of Roos and coworkers were also developed for the DKH2 Hamiltonian and have almost complete coverage of the periodic table (up to Cm).

For calculations with the X2C Hamiltonian, all-electron basis sets with the prefix “x2c-” (e.g. x2c-TZVPall) developed by Weigend and coworkers are available.[275, 690] The matching AuxJ basis set is “x2c/J” and AutoAux can be used as well.

4.3.4. Effective Core Potentials¶

Starting from version 2.8.0, ORCA features effective core potentials (ECPs). They are a good alternative to scalar relativistic all-electron calculations if heavy elements are involved. This pertains to geometry optimizations and energy calculations but may not be true for property calculations.

In order to reduce the computational effort, the usually highly contracted and chemically inert core basis functions can be eliminated by employing ECPs. ECP calculations comprise a “valence-only” basis and thus are subject to the frozen core approximation. Contributions due to the core orbitals are accounted for by an effective one-electron operator $U^{\text{core} }$ which replaces the interactions between core and valence electrons and accounts for the indistinguishability of the electrons. Its radial parts $U_l(r)$ are generally expressed as a linear combination of Gaussian functions, while the angular dependence is included through angular momentum projectors $|S^l_m\rangle$.

\[U^{\text{core} } = U_L(r) + \sum\limits_{l=0}^{L-1} \sum\limits_{m=-l}^{l}\left|S^l_m \rangle \left[U_l(r) - U_L(r)\right]\langle S^l_m\right|\]

\[U_l = \sum\limits_k d_{kl}r^{n_{kl} } \exp (-\alpha_{kl}r^2)\]

The maximum angular momentum $L$ is generally defined as $l_{\text{max} }^{\text{atom} } + 1$. The parameters $n_{kl}$, $\alpha_{kl}$ and $d_{kl}$ that are necessary to evaluate the ECP integrals have been published by various authors, among them the well-known Los Alamos (LANL) [367] and Stuttgart–Dresden (SD) [41, 94, 137, 138, 217, 218, 219, 220, 221, 222, 223, 261, 262, 279, 280, 281, 347, 348, 409, 432, 433, 437, 507, 508, 509, 523, 524, 561, 580, 581, 594, 595, 633, 671, 672, 673, 674, 675, 759, 774, 824, 825, 873, 880, 881, 901] parameter sets. Depending on the specific parametrization of the ECP, relativistic effects can be included in a semiempirical fashion in an otherwise nonrelativistic calculation. Introducing $U^{\text{core} }$ into the electronic Hamiltonian yields two types of ECP integrals, the local (or type-1) integrals that arise because of the maximum angular momentum potential $U_L$ and the semi-local (or type-2) integrals that result from the projected potential terms. The evaluation of these integrals in ORCA proceeds according to the scheme published by Flores-Moreno et al.[266].

A selection of ECP parameters and associated basis sets is directly accessible in ORCA through the internal ECP library (see Table 4.2 for a listing of keywords).

Table 4.2 Overview of library keywords for ECPs and associated basis sets available in ORCA.¶
ECP keyword	Core size[1]	Elements	Valence basis sets
		Recommended
def-ECP	78	Fr–Ra	Karlsruhe basis sets: def-TZVP, ma-def-TZVP
def-ECP	60	Ac–Lr	Karlsruhe basis sets: def-TZVP, ma-def-TZVP
def2-ECP	28	Rb–Xe	Karlsruhe basis sets: def2-SVP, def2-TZVP, etc. def2-SVPD, def2-TZVPD, etc. ma-def2-SVP, ma-def2-TZVP, etc.
	46	Cs–La
	28	Ce–Lu
	60	Hf–Rn
SK-MCDHF-RSC	10	Ca, Cu–Kr	Correlation-consistent basis sets: cc-pV$n$Z-PP, aug-cc-pV$n$Z-PP, cc-pCV$n$Z-PP, aug-cc-pCV$n$Z-PP, cc-pwCV$n$Z-PP, aug-cc-pwCV$n$Z-PP ($n=$ D, T, Q, 5) cc-pV$n$Z-PP ($n=$ D, T, Q)
	28	Sr–Xe
	46	Ba
	60	Hf–Rn
	78	Ra
	60	U
HayWadt[2]	10	Na–Cu	LANL-type basis sets: LANL2DZ, LANL2TZ, LANL2TZ(f), LANL08, LANL08(f)
	18	Zn
	28	Ga–Ag
	36	Cd
	46	In–La
	60	Hf–Au
	68	Hg–Tl
	78	Pb–Bi, U–Pu
dhf-ECP	28	Rb–Xe	dhf-type Karlsruhe basis sets: dhf-SVP, dhf-TZVP, etc.
	46	Cs–Ba
	60	Hf–Rn, U
vDZP-ECP	2	B–Mg	vDZP basis set. uniquely compiled for the use with vDZP
	10	Al–Zn
	28	Ga–Cd
	46	In–Lu
	60	Hf–Hg
	78	Tl–Rn
		Legacy definitions
def2-SD	28,MWB	Rb–Cd
	28,MDF[3]	In–Xe
	46,MWB	Cs–La
	60,MWB	Hf–Pt
	60,MDF[4]	Au–Rn
def-SD	28,MWB	Rb–Cd
	46,MWB	In–La
	28,MWB	Ce–Lu
	60,MWB	Hf–Pt
	60,MDF[4]	Au, Hg, Rn
	78,MWB	Tl–At
	78,MDF	Fr, Ra
	60,MWB	Ac–Lr
SDD	2,SDF	Li, Be
	2,MWB	B–Ne
	10,SDF	Na, Mg
	10,MWB	Al–Ca
	10,MDF	Sc–Ni
	10,MWB	Cu-Zn
	28,MWB	Ga–Sr
	28,MHF	Y–Cd
	28,MDF	Ge–Br, Rb–Xe
	46,MWB	In–Ba
	28,MWB	La–Lu
	60,MWB	Hf–Hg
	78,MWB	Tl–Rn
	60,MWB	Ac–Lr
LANL1	10	Na–Ar
	18	K–Zn
	28	Ga–Kr
	36	Rb–Cd
	46	In–Xe
	54	Cs–La
	68	Hf–Tl
	78	Pb, Bi
LANL2	10	K–Cu
	28	Rb–Ag
	46	Cs–La
	60	Hf–Au

Note

Some basis sets assign an ECP by default when requested through the simple input (but not through the %basis block): for example, “def2” basis sets use the def2-ECP. For others, see the footnotes under Table 7.9.

The simplest way to assign ECPs is by using the ECP keyword within the keyword line, although input through the %basis block is also possible (Advanced Specification of Effective Core Potentials). The ECP keyword itself assigns only the effective core potential, not a valence basis set! As an example for an explicitly named ECP you could use

! def2-TZVP def2-SD

This would assign the def2-SD ECP according to the definition given in the table above. Without the def2-SD keyword ORCA would default to def2-ECP.

4.4. Numerical Integration in ORCA¶

Starting from its version 5.0, ORCA has a new scheme for the quadratures used in numerical integration. It is based on the same general ideas which were used for the old grids, except that we used machine learning methods, together with some final hands-on optimization, to find the optimal parameters for all atoms up to the 6th row of the periodic table, with the 7th row being extrapolated from that. For further details look at Ref. [383]. We also realized that the COSX and DFT grids have overall different requirements, and these were optimized separately.

The big advantage of this new scheme is that it is significantly more accurate and robust than the old one, even if having the same number of grid points. We tested energies, geometries, frequencies, excitation energies and properties to develop three new grid schemes named: DEFGRID1, DEFGRID2 and DEFGRID3, that will automatically fix all grids that are used in the calculations. DEFGRID1 behaves essentially like the old defaults, but it is more robust. The second is the new default, and is expected to yield sufficiently small errors for all kinds of applications (see Section Details on the numerical integration grids for details). The last is a heavier, higher-quality grid, that is close to the limit if one considers an enormous grid as a reference.

In order to change from the default DEFGRID2, one just needs to add !DEFGRID1 or !DEFGRID3 to the main input.

It is also important to note that the COSX approximation is now the default for DFT, whenever HFexchange is neede. This can always be turned off by using !NOCOSX.

4.5. Input priority and processing order¶

In more complicated calculations, the input can get quite involved. Therefore it is worth knowing how it is internally processed by the program:

First, all the simple input lines (starting with “!”) are collected into a single string.
The program looks for all known keywords in a predefined order, regardless of the order in the input file.
An exception are basis sets: if two different orbital basis sets (e.g. ! def2-SVP def2-TZVP) are given, the latter takes priority. The same applies to auxiliary basis sets of the same type (e.g. ! def2/J SARC/J).
Some simple input keywords set multiple internal variables. Therefore, it is possible for one keyword to overwrite an option, set by another keyword. We have tried to resolve most such cases in a reasonable way (e.g. the more “specific” keyword should take precedence over a more “general” one) but it is difficult to forsee every combination of options.
Next, the block input is parsed in the order it is given in the input file.
Most block input keywords control a single variable (although there are exceptions). If a keyword is duplicated, the latter value is used.

Consider the following (bad) example:

! def2-TZVP UKS
%method
  functional BP86
  correlation C_LYP
  SpecialGridAtoms[1]  26, 27
  SpecialGridIntacc 8,  8,  8
  SpecialGridAtoms 28, 29
end
! PBE def2-SVP RKS

Using the rules above, one can figure out why it is equivalent to this one:

! UKS BLYP def2-SVP
%method
  SpecialGridAtoms 28, 29, 27
  SpecialGridIntacc 8,  8,  8
end

4.6. ORCA and Symmetry¶

For most of its life, ORCA did not take advantage of molecular symmetry. Starting from version 2.8 (released in September 2010), there has been at least limited use. On request (using the simple keyword UseSym for instance, see below), the program detects the point group, orients the molecule, cleans up the coordinates and produces symmetry-adapted molecular orbitals.

Only for geometry cleanup the full point group is taken into account. For all other purposes such as the construction of symmetry-adapted molecular orbitals and or to describe electronic states, only $D_{2h}$ and subgroups are currently supported. Here the use of symmetry helps to control the calculation and the interpretation of the results.

4.6.1. Getting started¶

Utilization of symmetry is turned on by the simple keyword UseSymmetry (which may be abbreviated by UseSym), or if a %Symmetry (or %Sym) input block is present in the input. ORCA will then automatically determine the point group, reorient and center the molecule to align its symmetry elements with the coordinate system, and replace the input structure by a geometry that corresponds exactly to this point group and which minimizes the sum of square distances between the atoms of both structures.

Any program that attempts to find the point group of an arbitrary atom cluster must be prepared to cope with some amount of numerical noise in the atom coordinates. ORCA by default allows each atom to deviate at most $10^{-4}$ atomic units from the ideal position that is consistent with the point group being examined. The rationale behind this value is the rounding error that occurs when the user feeds Cartesian coordinates with five significant digits after the decimal point into the program which otherwise represent an exact (symmetry-adapted) geometry. A threshold that is about one order of magnitude higher than the numerical noise in the coordinates is usually very safe.

If the maximum error in the Cartesian coordinates exceeds these $10^{-4}$ atomic units, the symmetry module in ORCA will fail to recognize the expected point group. The user is strongly advised to always make sure that the detected point group meets their expectations. If the point group reported by the symmetry module appears to be too low, the user may try to increase the detection threshold to $10^{-3}$ or $10^{-2}$ Bohr radii using option SymThresh in the %Symmetry input block:

%Sym SymThresh 0.01 End

A great method to obtain a structure with perfect symmetry avoiding any expensive calculation is to use the simple keywords ! NoIter XYZFile with an appropriate threshold. The structure in the resulting file with the extension .xyz may then be used as input for the actual calculation.

To give an illustrative example, coordinates for staggered ethane have been obtained by geometry optimization without using symmetry. If symmetry is turned on, point group $C_i$ is recognized instead of the expected point group $D_{3d}$ due to the remaining numerical noise. To counter this, the detection threshold is increased to $10^{-2}$ a. u. and a coordinate file with perfect symmetry is produced by the following input:

! RHF SVP NoIter XYZfile
%sym SymThresh 1.0e-2 end
*xyz 0 1
  C    -0.002822   -0.005082   -0.001782
  C    -0.723141   -1.252323   -0.511551
  H     0.017157    0.029421    1.100049
  H     1.042121    0.030085   -0.350586
  H    -0.495109    0.917401   -0.350838
  H    -0.743120   -1.286826   -1.613382
  H    -0.230855   -2.174806   -0.162495
  H    -1.768085   -1.287489   -0.162747
*

If ORCA fails to find the expected point group even though a value of $10^{-2}$ atomic units has been selected for SymThresh, the user is strongly advised to take a careful look at the structure by means of their favorite visualization tool before increasing this value any further. Look for any obvious distortions or even missing atoms. An especially tricky point may be the orientation of methyl groups or the conformation of floppy side chains. A small rotation about a single bond may be enough to push some atom positions above the limit. If the conformational deviations cannot be fixed using a molecular editor or modelling program, a possible alternative may be to pre-optimize the structure without symmetry using a less expensive method like PB86 and a small basis set like def2-SVP. Even several passes of pre-optimization and structure editing may be considered until all symmetry-equivalent side chains are locked in the same conformation so that ORCA finally detects the correct point group.

It is not recommended to run calculations using a value of SymThresh which is much too high or much too small since this may result in some really strange behavior of the symmetry module. Consider for instance the following input file which contains a perfectly octahedral geometry of a sulfur hexafluoride molecule. Its coordinates may be easily created by hand by placing the sulfur atom into the origin and two fluorine atoms on each coordinate axis at equal distances $r$ from the origin ($r=1.56$ Å or approximately $2.95$ atomic units). Using a value for SymThresh as large as $0.1$ Bohr radii works fine in this case, resulting in the correct point group O$_h$.

# Sulfur hexafluoride (SF6), point group Oh.
! BP86 def2-SVP
%Sym SymThresh 0.1 End
* xyz 0 1
S   0.00   0.00   0.00
F   1.56   0.00   0.00
F  -1.56   0.00   0.00
F   0.00   1.56   0.00
F   0.00  -1.56   0.00
F   0.00   0.00   1.56
F   0.00   0.00  -1.56
*

However, if SymThresh is increased further to $t=0.5$ atomic units, the point group detection algorithm breaks down (strange warnings are printed as a consequence) and the reported point group decreases to C$_i$ (in which the center of inversion is the only non-trivial symmetry element). This is because the center of inversion is easy to detect and this is done by one of the early checks. The breakdown of the point group recognition may be explained as follows. During the process of point group detection the symmetry module is of course unaware that the given input geometry is exact. Hence it will be treated as any other input structure. A value of $t=0.5$ Bohr radii for SymThresh means that the unknown exact atom position is located within a sphere of radius $t=0.5$ atomic units around the input atom position. The input distance $a=\sqrt{2}\,r$ between two adjacent fluorine atoms is approximately $a\approx 2.21$ Å $\approx 4.17$ a. u., so their unknown exact distance $d$ may vary in the following interval (see the diagram in Fig. 4.1):

\[d_{\rm min}=a-2t=3.17\:{\rm a. u.}\leq d\leq d_{\rm max}=a+2t=5.17\:{\rm a. u.}\]

Analogously, the unknown exact distance $d'$ between two opposite fluorine atoms with the input distance $a'=2r=5.90$ a. u. is:

\[d'_{\rm min}=a'-2t=4.90\:{\rm a. u.}\leq d'\leq d'_{\rm max}=a'+2t=6.90\:{\rm a. u.}\]

Since the possible intervals of $d$ and $d'$ overlap (due to $d_{\rm max}>d'_{\rm min}$), all fifteen F–F distances are considered equal. Since there is no solid with six vertices and fifteen equal inter-vertex distances in three dimensions, the point group detection algorithm fails.

../_images/symthresh.png — Fig. 4.1 The relation between the value $t$ of `SymThresh`, the distance $a$ of some input atom pair, and the allowed interval $[d_{\rm min},d_{\rm max}]$ for the distance $d$ between the exact atom positions. This interval has the width $d_{\rm max}-d_{\rm min}=4t$.¶

4.6.2. Geometry optimizations using symmetry¶

If a geometry optimization is performed with symmetry turned on, ORCA will first determine the point group of the starting structure and replace the geometry that is presumed to contain numerical noise with one that has perfect symmetry. Starting with ORCA 6, the optimizer will clean up the gradient at every step of the optimization if requested by setting option CleanUpGradient true in the %Symmetry input block. The gradient cleanup is done by projecting out all components that are not totally symmetric. This way the symmetry of the molecule cannot decrease during the optimization.

By default, the point group is determined from scratch again after the geometry has been updated at every step of the optimization. This behaviour may be switched off by setting option SymRelaxOpt false in the %Symmetry input block. In this case the point group of the molecule is actually frozen during the entire optimization.

The following table summarizes the behaviour of the optimizer depending on the options SymRelaxOpt and CleanUpGradient:

`SymRelaxOpt`	`CleanUpGradient`	Behaviour
`true`	`true`	Symmetry may increase but not decrease.
`true`	`false`	Symmetry may change freely.
`false`	`true`	Symmetry will be frozen.
`false`	`false`	Setting not recommended.

Setting both switches false would allow the point group to change during the optimization but at the same time, a change would be impossible to detect. Therefore this setting is strongly discouraged.

4.6.3. Default alignment of the symmetry elements with the coordinate system¶

If ORCA determines the point group of a molecule and the user has not selected any special options, the following principles apply to the manner in which the symmetry elements of the full point group are aligned with the coordinate system:

The center of mass of the molecule will be shifted into the origin by default.[5] If the point group leaves one unique vertex invariant to all symmetry operations, the center of mass agrees with this vertex. This is the case for all point groups except $C_s$, $C_n$ $(n\ge 1)$, $C_{nv}$ $(n\ge 2)$, and $C_{\infty v}$.
If the molecule exhibits a unique axis of symmetry with the highest number of positions, this axis will become the $z$ axis. This applies to all point groups except $C_1$, $C_i$, $C_s$, $D_2$, $D_{2h}$, the cubic point groups, and $K_h$.
For point group $C_s$, the mirror plane will become the $xy$ plane.
For point groups $C_{nv}$ $(n\ge 2)$, one of the vertical mirror planes will become the $xz$ plane.
For point groups $D_n$ $(n\ge 3)$, $D_{nh}$ $(n\ge 3)$, and $D_{nd}$ $(n\ge 2)$, one of the two-fold rotation axes perpendicular to the axis with the highest number of positions will become the $x$ axis.
For point groups $D_2$, $D_{2h}$, $T$, and $T_h$, the three mutually orthogonal $C_2$ axes will become the coordinate axes.
For point groups $T_d$, $O$, and $O_h$, the three mutually orthogonal four-fold rotation or rotation-reflection axes will become the coordinate axes.
Finally, for point groups $I$ and $I_h$, one of the five sets of three mutually orthogonal $C_2$ axes will become the coordinate axes. The pair of $C_5$ or $S_{10}$ axes closest to the $z$ axis will be located in the $yz$ plane.
In general the orientation of the molecule will be changed as little as possible to meet the criteria above. If the input geometry meets these criteria already, the molecule will not be moved or rotated at all.

If the point group of the system is $D_{nd}$ with $n\ge 2$ or $T_d$ and the user has selected subgroup $C_{2v}$ using option PreferC2v, the following rules apply instead:

For point group $D_{nd}$ with $n\ge 2$, one of the diagonal mirror planes will become the $xz$ plane.
For point group $T_d$, one of the diagonal mirror planes containing the $z$ axis will become the $xz$ plane, i. e. the molecule will be rotated by 45 degrees about the $z$ axis compared to the default orientation.

Table 4.3 gives an overview over all point groups and the way in which the symmetry elements of the reduced point group (the largest common subgroup of $D_{2h}$) are aligned with the coordinate system.

Table 4.3 Point groups and corresponding subgroups suitable for electronic-structure calculations.¶
Full	Index	Unique	Consistent	Chosen	Alignment
point	$n$	center[6]	with planar	subgroup	of the
group			molecule[7]		subgroup[8]
$C_1$		no	no	$C_1$
$C_i$		$i$	no	$C_i$
$C_s$		no	yes	$C_s$
$C_n$	odd	no	no	$C_1$
	even	no	no	$C_2$	$z$ axis
$C_{nv}$	odd	no	no	$C_s$	$xz$ plane
	even	no	for $n=2$	$C_{2v}$	$z$, $xz$, $yz$
$C_{nh}$	odd	yes	yes	$C_s$	$xy$ plane
	even	$i$	yes	$C_{2h}$	$z$, $xy$
$D_n$	odd	yes	no	$C_2$	$x$ axis
	even	yes	no	$D_2$
$D_{nh}$	odd	yes	yes	$C_{2v}$	$x$, $xy$, $xz$
	even	$i$	yes	$D_{2h}$
$D_{nd}$	odd	$i$	no	$C_{2h}$	$x$, $yz$
	even	yes	no	$D_2$
				$C_{2v}$	$z$, $xz$, $yz$
$S_{2n}$	odd	$i$	no	$C_i$
	even	yes	no	$C_2$	$z$ axis
$T$		yes	no	$D_2$
$T_h$		$i$	no	$D_{2h}$
$T_d$		yes	no	$D_2$
				$C_{2v}$	$z$, $xz$, $yz$
$O$		yes	no	$D_2$
$O_h$		$i$	no	$D_{2h}$
$I$		yes	no	$D_2$
$I_h$		$i$	no	$D_{2h}$
$C_{\infty v}$		no	no	$C_{2v}$	$z$, $xz$, $yz$
$D_{\infty h}$		$i$	no	$D_{2h}$
$K_h$		$i$	no	$D_{2h}$

4.6.4. Irreducible representations of $D_{2h}$ and subgroups¶

Table 4.4, Table 4.5, and Table 4.6 contain lists of the irreducible representations (also called species) and the corresponding characters of the point groups supported for electronic structure calculations in ORCA, and the product tables of these irreducible representations. Where the data depends on the alignment of the symmetry elements with the coordinate system, Mulliken’s recommendations [600] are followed. This approach is in line with the recommendations by the IUPAC [771].

Table 4.4 Species and species product table of point group $C_{2v}$. The species table for $C_{2v}$ corresponds to Table III in [600]. The directions of the two-fold axis and the mirror planes in each column are related to each other by cyclic permutations.¶
$\begin{array}{@{}c@{\hspace{10mm}}c@{}} \begin{array}[b]{\|c\|cccc\|}\hline & & C_2(z) & \sigma_v(xz) & \sigma_v(yz) \\ C_{2v} & E & C_2(x) & \sigma_v(xy) & \sigma_v(xz) \\ & & C_2(y) & \sigma_v(yz) & \sigma_v(xy) \\\hline A_1 & +1 & +1 & +1 & +1 \\ A_2 & +1 & +1 & -1 & -1 \\ B_1 & +1 & -1 & +1 & -1 \\ B_2 & +1 & -1 & -1 & +1 \\\hline \end{array} & \begin{array}[b]{\|c\|cccc\|}\hline \times & A_1 & A_2 & B_1 & B_2 \\\hline A_1 & A_1 & A_2 & B_1 & B_2 \\ A_2 & A_2 & A_1 & B_2 & B_1 \\ B_1 & B_1 & B_2 & A_1 & A_2 \\ B_2 & B_2 & B_1 & A_2 & A_1 \\\hline \end{array} \end{array}$

Table 4.5 Species and species product table of point group $D_2$. The species table for $D_2$ has been obtained by dropping the center of inversion and the mirror planes from the species table for $D_{2h}$ (see Table 4.6).¶
$\begin{array}{@{}c@{\hspace{10mm}}c@{}} \begin{array}{\|l\|cccc\|}\hline D_2 & E & C_2(z) & C_2(y) & C_2(x) \\\hline A & +1 & +1 & +1 & +1 \\ B_1 & +1 & +1 & -1 & -1 \\ B_2 & +1 & -1 & +1 & -1 \\ B_3 & +1 & -1 & -1 & +1 \\\hline \end{array} & \begin{array}{\|c\|cccc\|}\hline \times & A & B_1 & B_2 & B_3 \\\hline A & A & B_1 & B_2 & B_3 \\ B_1 & B_1 & A & B_3 & B_2 \\ B_2 & B_2 & B_3 & A & B_1 \\ B_3 & B_3 & B_2 & B_1 & A \\\hline \end{array} \end{array}$

Table 4.6 Species and species product table of point group $D_{2h}$. The species table for $D_{2h}$ corresponds to Table IV in [600].¶
\(\begin{array}{@{}c@{}} \begin{array}{\|l\|cccccccc\|}\hline D_{2h} & E & C_2(z) & C_2(y) & C_2(x) & i & \sigma(xy) & \sigma(xz) & \sigma(yz) \\\hline A_g & +1 & +1 & +1 & +1 & +1 & +1 & +1 & +1 \\ B_{1g} & +1 & +1 & -1 & -1 & +1 & +1 & -1 & -1 \\ B_{2g} & +1 & -1 & +1 & -1 & +1 & -1 & +1 & -1 \\ B_{3g} & +1 & -1 & -1 & +1 & +1 & -1 & -1 & +1 \\ A_u & +1 & +1 & +1 & +1 & -1 & -1 & -1 & -1 \\ B_{1u} & +1 & +1 & -1 & -1 & -1 & -1 & +1 & +1 \\ B_{2u} & +1 & -1 & +1 & -1 & -1 & +1 & -1 & +1 \\ B_{3u} & +1 & -1 & -1 & +1 & -1 & +1 & +1 & -1 \\\hline \end{array} \\[3mm] \begin{array}{\|c\|cccccccc\|}\hline \times & A_g & B_{1g} & B_{2g} & B_{3g} & A_u & B_{1u} & B_{2u} & B_{3u} \\\hline A_g & A_g & B_{1g} & B_{2g} & B_{3g} & A_u & B_{1u} & B_{2u} & B_{3u} \\ B_{1g} & B_{1g} & A_g & B_{3g} & B_{2g} & B_{1u} & A_u & B_{3u} & B_{2u} \\ B_{2g} & B_{2g} & B_{3g} & A_g & B_{1g} & B_{2u} & B_{3u} & A_u & B_{1u} \\ B_{3g} & B_{3g} & B_{2g} & B_{1g} & A_g & B_{3u} & B_{2u} & B_{1u} & A_u \\ A_u & A_u & B_{1u} & B_{2u} & B_{3u} & A_g & B_{1g} & B_{2g} & B_{3g} \\ B_{1u} & B_{1u} & A_u & B_{3u} & B_{2u} & B_{1g} & A_g & B_{3g} & B_{2u} \\ B_{2u} & B_{2u} & B_{3u} & A_u & B_{1u} & B_{2g} & B_{3g} & A_g & B_{1u} \\ B_{3u} & B_{3u} & B_{2u} & B_{1u} & A_u & B_{3g} & B_{2g} & B_{1g} & A_g \\\hline \end{array} \end{array}\)

4.6.5. Options available in the `%Symmetry` input block¶

Table 4.7 contains a list of the options available in the %Symmetry (or %Sym) input block. Options SymThresh and SymRelax (same as SymRelaxSCF below) can also be accessed in the %Method input block for backward compatibility. This use is deprecated and not recommended in new input files, however.

Table 4.7 List of options in the `%Symmetry` (`%Sym`) input block¶
Option	Type	Default	Description
`UseSymmetry`	Boolean	`True`	By setting this option to `False`, symmetry may be switched off even though the `%Symmetry` block is present in the input file.
`UseSym`	Boolean	`True`	Same as `UseSymmetry`.
`SymThresh`	Real	$10^{-4}$	Two vertices with a distance shorter than this threshold (in atomic units) are considered identical during point group recognition.
`PreferC2v`	Boolean	`False`	Indicates whether to prefer subgroup $C_{2v}$ over $D_2$ for electronic-structure calculations where both choices are appropriate (point groups $D_{nd}$ with odd $n$ and $T_d$).
`PointGroup`	String	Empty string	If the user specifies a point group using this option, point group recognition will be skipped and the user must make sure that the molecule is oriented in the coordinate system in agreement with the conventions in Section 4.6.3. Note that the point group label must be enclosed in double quotes. Otherwise ORCA will complain about an invalid assignment.
`SymRelaxSCF`	Boolean	`False`	Indicates whether orbital occupation numbers of each irreducible representation are allowed to change during SCF.
`SymRelaxOpt`	Boolean	`True`	Indicates whether the point group will be determined from scratch in every step of a geometry optimization. A value of `True` will allow the point group to change in an arbitrary manner. Otherwise the initial point group will be imposed at every step no matter how far the distances between the current and the ideal structure exceed `SymThresh`.
`CleanUpCoords`	Boolean	`True`	Determines whether the molecular geometry will be cleaned up using the automatically detected or user-specified point group. Even if `CleanUpCoords` is `False`, symmetrized coordinates will still be computed temporarily and a warning will be printed if the largest deviation from the original geometry exceeds `SymThresh`.
`CleanUpGeom`	Boolean	`True`	Same as `CleanUpCoords`.
`CleanUpGrad`	Boolean	`True`	Indicates whether the full point group of the molecule shall be used to remove all non-totally symmetric components from the gradient. This ensures that the point group will not decrease throughout the optimization.
`CleanUpGradient`	Boolean	`True`	Same as `CleanUpGrad`.
`Print`	Integer	1	Determines the output size for symmetry handling in general and point group detection in particular; 0 – No output during point group detection; 1 – Normal output; 2 – Detailed information; 3 – Debug print.
`PrtSALC`	Integer	0	Specifies the output size for the construction of symmetry-adapted linear combinations (SALCs) of atomic orbitals; 0 – No output for symmetry-adapted orbitals; 1 – Normal output; 2 – Detailed information (e. g. the SALCs themselves); 3 – Debug print.

4.7. Jobs with Multiple Steps¶

ORCA supports input files with multiple jobs. This feature is designed to simplify series of closely related calculations on the same molecule or calculations on different molecules. The objectives for implementing this feature include:

Calculate of a molecular property using different theoretical methods and/or basis sets for one molecule.
Calculations on a series of molecules with identical settings.
Geometry optimization followed by more accurate single points and perhaps property calculations.
Crude calculations to provide good starting orbitals that may then be used for subsequent calculations with larger basis sets.

For example consider the following job that in the first step computes the g-tensor of BO at the LDA level, and in the second step using the BP86 functional.

# -----------------------------------------------------
! LSD DEF2-SVP TightSCF KeepInts
# -----------------------------------------------------
%eprnmr gtensor 1 end

* int 0 2
   B  0  0  0   0      0  0
   O  1  0  0   1.2049 0  0
*

# *************************************************
# ****** This starts the input for the next job   *
# *************************************************
$new_job
# --------------------------------------------------
! BP86 DEF2-SVP SmallPrint ReadInts NoKeepInts
# --------------------------------------------------
%eprnmr gtensor 1 end

* int 0 2
   B  0  0  0   0      0  0
   O  1  0  0   1.2049 0  0
*

What happens if you use the $new_job feature is that all calculation flags for the actual job are transferred from the previous job and that only the changes in the settings must be input by the user. Thus if you turn on some flags for one calculation that you do not want for the next, you have to turn them off again yourself (for example the use of the RI approximation)! In addition, the default is that the new job takes the orbitals from the old job as input. If you do not want this you have to overwrite this default by specifying your desired guess explicitly.

4.7.1. Changing the default BaseName¶

Normally the output files for MyJob.inp are returned in MyJob.xxx (any xxx, for example xxx=out). Sometimes, and in particular in multistep jobs, you will want to change this behavior. To this end there is the variable %base that can be user controlled. All filenames (also scratch files) will then be based on this default name. For example, using the following setting, the output files for the current job would be job1.xxx (e.g. job1.gbw, job1.densities, etc.).

%base "job1"

\(+\) before “G”	Include diffuse functions on all atoms except H (e.g. 6-31\(+\)G)
\(++\) before “G”	Include diffuse functions on all atoms. Works only when H polarization is already included, e.g. 6-31\(++\)G(d,p)

pc-\(n\)	(\(n=\) 0, 1, 2, 3, 4) “Polarization-consistent” generally contracted basis sets (H–Kr) of up to quintuple-zeta quality, optimized for SCF calculations
aug-pc-\(n\)	As above, augmented by diffuse functions
pcseg-\(n\)	Segmented PC basis sets (H–Kr), DFT-optimized
aug-pcseg-\(n\)	As above, augmented by diffuse functions
pcSseg-\(n\)	Segmented contracted basis sets (H–Kr) optimized for nuclear magnetic shielding
aug-pcSseg-\(n\)	As above, augmented by diffuse functions
pcJ-\(n\)	Segmented contracted basis sets (H–Ar) optimized for spin-spin coupling constants
aug-pcJ-\(n\)	As above, augmented by diffuse functions

HGBS-\(m\)	(\(m=\) 5, 7, 9) Lehtolas hydrogenic Gaussian basis sets optimized to the energy threshold \(m\) (H-Og)
HGBSP\(n\)-\(m\)	(\(n=\) 1, 2, 3; \(m=\) 5, 7, 9) Variants with \(n\) polarization shells

Keyword	Input block	Variable	Comment
DEFGRID\(n\) (\(n=1\)–3)	METHOD	GRID	Selects the integration grids
NOFINALGRIDX			Turn off the final grid in COSX (not recommended)

wB97	Head-Gordon’s fully variable DF \(\omega\)B97
wB97X	Head-Gordon’s DF \(\omega\)B97X with minimal Fock exchange
wB97X-D3	Chai’s refit incl. D3 in its zero-damping version
wB97X-D4	Modified version of \(\omega\)B97X-V with DFT-D4 correction by Najibi and Goerigk
wB97X-D4rev	Modified version of \(\omega\)B97X-V with DFT-D4 correction by Grimme et al.
wB97X-V	Head-Gordon’s DF \(\omega\)B97X-V with VV10 nonlocal correlation
wB97X-D3BJ	Modified version of \(\omega\)B97X-V with D3BJ correction by Najibi and Goerigk
wB97M-V	Head-Gordon’s DF \(\omega\)B97M-V with VV10 nonlocal correlation
wB97M-D3BJ	Modified version of \(\omega\)B97M-V with D3BJ correction by Najibi and Goerigk
wB97M-D4	Modified version of \(\omega\)B97M-V with DFT-D4 correction by Najibi and Goerigk
wB97M-D4rev	Modified version of \(\omega\)B97M-V with DFT-D4 correction by Grimme et al.
CAM-B3LYP	Handy’s fit
LC-BLYP	Hirao’s original application
LC-PBE	range-separated PBE-based hybrid functional with 100% Fock exchange in the long-range regime
wr2SCAN	Range-separated hybrid variant of \(r^2\) SCAN with 0-100% HF exchange

wB97X-2	Chai and Head-Gordon’s \(\omega\)B97X-2(TQZ) range-separated GGA-based DHDF with spin-component scaling
SCS/SOS-B2PLYP21	spin-opposite scaled version of B2PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS fit gave SOS version; SOS only applies to the CIS(D) component)
SCS-PBE-QIDH	spin-component scaled version of PBE-QIDH optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-PBE-QIDH	spin-opposite scaled version of PBE-QIDH optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-B2GP-PLYP21	spin-component scaled version of B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-B2GP-PLYP21	spin-opposite scaled version of B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS/SOS-wB2PLYP	spin-opposite scaled version of \(\omega\)B2PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS fit gave SOS version; SOS only applies to the CIS(D) component)
SCS-wB2GP-PLYP	spin-component scaled version of \(\omega\)B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wB2GP-PLYP	spin-opposite scaled version of \(\omega\)B2GP-PLYP optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-RSX-QIDH	spin-component scaled version of RSX-QIDH optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-RSX-QIDH	spin-opposite scaled version of RSX-QIDH optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-wB88PP86	spin-component scaled version of \(\omega\)B88PPBE86 optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wB88PP86	spin-opposite scaled version of \(\omega\)B88PPBE86 optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)
SCS-wPBEPP86	spin-component scaled version of \(\omega\)PBEPPBE86 optimized for excited states by Casanova-Páez and Goerigk (SCS only applies to the CIS(D) component)
SOS-wPBEPP86	spin-opposite scaled version of \(\omega\)PBEPPBE86 optimized for excited states by Casanova-Páez and Goerigk (SOS only applies to the CIS(D) component)

AHGBS-\(m\)	(\(m=\) 5, 7, 9) Variants augmented by diffuse functions
AHGBSP\(n\)-\(m\)	(\(n=\) 1, 2, 3; \(m=\) 5, 7, 9)

Sapporo-\(n\)ZP-2012	(\(n=\) D, T, Q) All-electron generally contracted non-relativistic basis sets (H–Xe)
Sapporo-DKH3-\(n\)ZP-2012	(\(n=\) D, T, Q) All-electron basis sets optimized for the DKH3 Hamiltonian and finite nucleus (K–Rn)

apr-cc-pV(Q+d)Z	Augmented with sp diffuse functions on Li–Ca
may-cc-pV(\(n\)+d)Z	(\(n=\) T, Q): sp (T), spd (Q) on Li–Ca
jun-cc-pV(\(n\)+d)Z	(\(n=\) D, T, Q): sp (D), spd (T), spdf (Q) on Li–Ca
jul-cc-pV(\(n\)+d)Z	(\(n=\) D, T, Q): spd (D), spdf (T), spdfg (Q) on Li–Ca
maug-cc-pV(\(n\)+d)Z	same as jun-, may-, and apr- for \(n=\) D, T, and Q, respectively

cc-pV\(n\)Z-DK	(\(n=\) D, T, Q, 5) Correlation-consistent all-electron basis sets for use with the 2nd-order Douglas-Kroll-Hess Hamiltonian
aug-cc-pV\(n\)Z-DK	(\(n=\) D, T, Q, 5) as above, augmented with diffuse functions
cc-pwCV\(n\)Z-DK	(\(n=\) D, T, Q, 5) DK versions of weighted core correlation-consistent basis sets
aug-cc-pwCV\(n\)Z-DK	(\(n=\) D, T, Q, 5) weighted-core DK basis sets with diffuse functions
cc-pV\(n\)Z-DK3	(\(n=\) D, T, Q) Correlation-consistent all-electron basis sets for lanthanides and actinides with the 3rd-order Douglas-Kroll-Hess Hamiltonian
cc-pwCV\(n\)Z-DK3	(\(n=\) D, T, Q) DK versions of weighted core correlation-consistent basis sets for lanthanides and actinides

cc-pV\(n\)Z-PP	(\(n=\) D, T, Q, 5) Correlation-consistent basis sets combined with SK-MCDHF-RSC effective core potentials
aug-cc-pV\(n\)Z-PP	(\(n=\) D, T, Q, 5) as above, augmented with diffuse functions
cc-pwCV\(n\)Z-PP	(\(n=\) D, T, Q, 5) with weighted core functions
aug-cc-pwCV\(n\)Z-PP	(\(n=\) D, T, Q, 5) as above, augmented with diffuse functions

cc-pV\(n\)Z-F12	(\(n=\) D, T, Q) Special orbital basis sets for F12 calculations (larger than the regular D, T, Q-zeta basis sets!)
cc-pCV\(n\)Z-F12	(\(n=\) D, T, Q) with core polarization functions
cc-pV\(n\)Z-PP-F12	(\(n=\) D, T, Q) ECP-based versions
cc-pV\(n\)Z-F12-CABS	(\(n=\) D, T, Q) Near-complete auxiliary basis sets for F12 calculations
cc-pV\(n\)Z-F12-OptRI	(\(n=\) D, T, Q) identical to the cc-pV\(n\)Z-F12-CABS basis above
cc-pCV\(n\)Z-F12-OptRI	(\(n=\) D, T, Q)
cc-pV\(n\)Z-PP-F12-OptRI	(\(n=\) D, T, Q)
aug-cc-pV\(n\)Z-PP-OptRI	(\(n=\) D, T, Q, 5)
aug-cc-pwCV\(n\)Z-PP-OptRI	(\(n=\) D, T, Q, 5)

ANO-pV\(n\)Z	(\(n=\) D, T, Q, 5, 6). Our newly contracted ANO basis sets on the basis of the cc-pV6Z (or pc-4 where missing) primitives. These are very accurate basis sets that are significantly better than the cc-pV\(n\)Z counterparts for the same number of basis functions (but much larger number of primitives of course).
saug-ANO-pV\(n\)Z	(\(n=\) D, T, Q, 5) augmentation with a single set of sp functions. Greatly enhances the accuracy of the SCF energies but not for correlation energies.
aug-ANO-pV\(n\)Z	(\(n=\) D, T, Q, 5) full augmentation with spd, spdf, spdfg set of polarization functions. Almost as expensive as the next higher basis set. In fact, aug-ANO-pV\(n\)Z \(=\) ANO-pV(\(n+1\))Z with the highest angular momentum polarization function deleted.

Def2/JK	Coulomb\(+\)Exchange fitting for all def2 basis sets
Def2/JKsmall	reduced version of the above
cc-pV\(n\)Z/JK	(\(n=\) T, Q, 5) for the respective cc-pV\(n\)Z orbital basis
aug-cc-pV\(n\)Z/JK	(\(n=\) T, Q, 5) for the respective aug-cc-pV\(n\)Z orbital basis

Full	Index	Unique	Consistent	Chosen	Alignment
point	\(n\)	center[6]	with planar	subgroup	of the
group			molecule[7]		subgroup[8]
\(C_1\)		no	no	\(C_1\)
\(C_i\)		\(i\)	no	\(C_i\)
\(C_s\)		no	yes	\(C_s\)
\(C_n\)	odd	no	no	\(C_1\)
	even	no	no	\(C_2\)	\(z\) axis
\(C_{nv}\)	odd	no	no	\(C_s\)	\(xz\) plane
	even	no	for \(n=2\)	\(C_{2v}\)	\(z\), \(xz\), \(yz\)
\(C_{nh}\)	odd	yes	yes	\(C_s\)	\(xy\) plane
	even	\(i\)	yes	\(C_{2h}\)	\(z\), \(xy\)
\(D_n\)	odd	yes	no	\(C_2\)	\(x\) axis
	even	yes	no	\(D_2\)
\(D_{nh}\)	odd	yes	yes	\(C_{2v}\)	\(x\), \(xy\), \(xz\)
	even	\(i\)	yes	\(D_{2h}\)
\(D_{nd}\)	odd	\(i\)	no	\(C_{2h}\)	\(x\), \(yz\)
	even	yes	no	\(D_2\)
				\(C_{2v}\)	\(z\), \(xz\), \(yz\)
\(S_{2n}\)	odd	\(i\)	no	\(C_i\)
	even	yes	no	\(C_2\)	\(z\) axis
\(T\)		yes	no	\(D_2\)
\(T_h\)		\(i\)	no	\(D_{2h}\)
\(T_d\)		yes	no	\(D_2\)
				\(C_{2v}\)	\(z\), \(xz\), \(yz\)
\(O\)		yes	no	\(D_2\)
\(O_h\)		\(i\)	no	\(D_{2h}\)
\(I\)		yes	no	\(D_2\)
\(I_h\)		\(i\)	no	\(D_{2h}\)
\(C_{\infty v}\)		no	no	\(C_{2v}\)	\(z\), \(xz\), \(yz\)
\(D_{\infty h}\)		\(i\)	no	\(D_{2h}\)
\(K_h\)		\(i\)	no	\(D_{2h}\)

4. General Structure of the Input File¶

4.1. Input Blocks¶

4.2. Keyword Lines¶

4.2.1. Main Methods and Options¶

4.2.1.1. Runtypes¶

4.2.1.2. Atomic mass/weight handling¶

4.2.1.3. Symmetry handling¶

4.2.1.4. Second order many body perturbation theory¶

4.2.1.5. High-level single reference methods¶

4.2.1.6. AUTOCI single reference methods¶

4.2.1.7. Local correlation methods¶

4.2.1.8. Accuracy control for local correlation methods¶

4.2.1.9. Automatic basis set extrapolation¶

4.2.1.10. High-level methods for excited states as implemented in the MDCI module¶

4.2.1.11. CASSCF related options¶

4.2.1.12. (internally contracted) Multireference methods beyond NEVPT2/CASPT2¶

4.2.1.13. (uncontracted) Multireference methods¶

4.2.1.14. Frozen core features¶

4.2.1.15. Semiempirical methods¶

4.2.1.16. Algorithmic variations, options, add-ons, modifiers, …¶

4.2.1.17. Initial guess options¶

4.2.1.18. Basis-set related keywords¶

4.2.1.19. Relativistic options¶

4.2.1.20. Grid options¶

4.2.1.21. Convergence thresholds¶

4.2.1.22. Convergence acceleration¶

4.2.1.23. Convergence strategies¶

4.2.1.24. Spin-orbit coupling¶

4.2.1.25. Miscellaneous options¶

4.2.1.26. Output control¶

4.2.1.27. Nudged Elastic Band methods¶

4.2.1.28. Compression and storage¶

4.2.1.29. Global memory use¶

4.2.2. Density Functional Methods¶

4.2.2.1. Local and gradient corrected functionals¶

4.2.2.2. Hybrid functionals¶

4.2.2.3. Meta-GGA and hybrid meta-GGA functionals¶

4.2.2.4. Range-separated hybrid functionals¶

4.2.2.5. Perturbatively corrected double-hybrid functionals¶

4.2.2.6. Range-separated double-hybrid functionals¶

4.2.2.7. Global and range-separated double-hybrid functionals with spin-component and spin-opposite scaling¶

4.2.2.8. Composite Methods¶

4.2.2.9. Dispersion corrections¶

4.2.2.10. Non-local correlation¶

4.3. Basis Sets¶

4.3.1. Standard basis set library¶

4.3.1.1. Pople-style basis sets¶

4.3.1.2. The def2 basis sets of the Karlsruhe group¶

4.3.1.3. Older (“def”) Ahlrichs basis sets¶

4.3.1.4. Diffuse def2 basis sets¶

4.3.1.5. Karlsruhe basis sets with Dirac–Fock ECPs¶

4.3.1.6. Relativistically recontracted Karlsruhe basis sets¶

4.3.1.7. SARC basis sets¶

4.3.1.8. SARC2 basis sets for the lanthanides¶

4.3.1.9. Jensen basis sets¶

4.3.1.10. Lehtolas hydrogenic Gaussian basis sets¶

4.3.1.11. Sapporo basis sets¶

4.3.1.12. Correlation-consistent basis sets¶

4.3.1.13. Partially augmented correlation-consistent basis sets¶

4.3.1.14. DKH versions of correlation-consistent basis sets¶

4.3.1.15. ECP-based versions of correlation-consistent basis sets¶

4.3.1.16. F12 and F12-CABS basis sets¶

4.3.1.17. Atomic Natural Orbital basis sets¶

4.3.1.18. Miscellaneous and specialized basis sets¶

4.3.2. Auxiliary basis sets¶

4.3.2.1. Auxiliary basis sets for Coulomb fitting¶

4.3.2.2. Auxiliary basis sets for simultaneously fitting Coulomb and exchange¶

4.3.2.3. Auxiliary basis sets for correlation calculations¶

4.3.3. Use of scalar relativistic basis sets¶

4.3.4. Effective Core Potentials¶

4.4. Numerical Integration in ORCA¶

4.5. Input priority and processing order¶

4.6. ORCA and Symmetry¶

4.6.1. Getting started¶

4.6.2. Geometry optimizations using symmetry¶

4.6.3. Default alignment of the symmetry elements with the coordinate system¶

4.6.4. Irreducible representations of \(D_{2h}\) and subgroups¶

4.6.5. Options available in the %Symmetry input block¶

4.7. Jobs with Multiple Steps¶

4.7.1. Changing the default BaseName¶

4.6.5. Options available in the `%Symmetry` input block¶