(chapter:structure)= # 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: ```orca ! 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: ```orca # 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: ```orca 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. (sec:inputblocks.structure)= ## Input Blocks The following blocks exist: :::{list-table} * - `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: ```orca %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: ```orca VariableName Value ``` Some variables are actually arrays. In this case several possible assignments are useful: ```orca 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: ```orca 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. (sec:keywordlines.structure)= ## 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. ```orca ! Keywords ``` (sec:keywordlines.main.structure)= ### Main Methods and Options {numref}`table:list_of_keywords` 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. :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.15}\Y{0.55} ::: (table:list_of_keywords)= :::{list-table} Main keywords that can be used in the simple input of ORCA. :header-rows: 1 * - Keyword - Input block - Variable - Comment * - HF - METHOD - METHOD - Selects the Hartree-Fock method * - DFT - - - Selects the DFT method (see section {ref}`sec:keywordlines.dft.structure` for a list of functionals) * - FOD - - - FOD analysis (see {ref}`sec:scfconv.temp.fod.detailed`) employing default settings (TPSS/def2-TZVP, TightSCF, SmearTemp = 5000 K) ::: #### Runtypes :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.15}\Y{0.55} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Atomic mass/weight handling :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.15}\Y{0.55} ::: :::{list-table} :header-rows: 1 * - 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. ::: #### Symmetry handling :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.15}\Y{0.55} ::: :::{list-table} :header-rows: 1 * - Keyword - Input block - Variable - Comment * - UseSym - - - Turns on the use of molecular symmetry (see section {ref}`sec:symmetry.structure`). *THIS IS VERY RUDIMENTARY!* * - NoUseSym - - - Turns symmetry off ::: #### Second order many body perturbation theory :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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) ::: #### High-level single reference methods These are implemented in the MDCI module. They can be run in a number of technical variants. :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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. #### AUTOCI single reference methods These single reference correlation methods are available in the AUTOCI. :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### 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 {ref}`sec:energygradients.ccsd.typical`. :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### 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. :::{tabularcolumns} \Y{0.25}\Y{0.15}\Y{0.15}\Y{0.45} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Automatic basis set extrapolation :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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\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. ::: #### 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. :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.2}\Y{0.45} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Basis-set related keywords :::{tabularcolumns} \Y{0.225}\Y{0.15}\Y{0.225}\Y{0.4} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Relativistic options There are several variants of scalar relativistic Hamiltonians to use in all electron calculations. See {ref}`sec:relativistic.detailed` for details. :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.25}\Y{0.45} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Grid options :::{list-table} :header-rows: 1 * - 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) ::: #### 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. :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.2}\Y{0.45} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### 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. :::{list-table} :header-rows: 1 * - 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 ::: #### Convergence strategies (does not modify the convergence criteria) :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - Keyword - Input block - Variable - 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 [\[sec:solvationmodels.detailed\]](#sec:solvationmodels.detailed){reference-type="ref" reference="sec:solvationmodels.detailed"} for a list of solvents). If no solvent is given, infinity (a conductor) is assumed. ::: #### Spin-orbit coupling :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} :header-rows: 1 * - 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. ::: #### Miscellaneous options :::{tabularcolumns} \Y{0.15}\Y{0.15}\Y{0.15}\Y{0.55} ::: :::{list-table} :header-rows: 1 * - 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 {ref}`sec:scfconv.temp.fod.detailed`) 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 ::: #### Output control :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.2}\Y{0.45} ::: :::{list-table} :header-rows: 1 * - 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 ::: #### Nudged Elastic Band methods :::{tabularcolumns} \Y{0.2}\Y{0.15}\Y{0.15}\Y{0.5} ::: :::{list-table} * - 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 ::: #### 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. ::: (sec:keywordlines.globalmemuse.structure)= #### 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: ```orca %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. (sec:keywordlines.dft.structure)= ### 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 [\[sec:model.dft.functionals.detailed\]](#sec:model.dft.functionals.detailed){reference-type="ref" reference="sec:model.dft.functionals.detailed"} #### Local and gradient corrected functionals :::{list-table} * - 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 ::: #### Hybrid functionals :::{list-table} * - 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 ::: #### Meta-GGA and hybrid meta-GGA functionals :::{list-table} * - 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 ::: #### Range-separated hybrid functionals :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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 ::: #### Perturbatively corrected double-hybrid functionals Add the prefix RI- or DLPNO- to use the respective approximation for the MP2 part. :::{list-table} * - 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 ::: #### Range-separated double-hybrid functionals Add the prefix RI- or DLPNO- to use the respective approximation for the MP2 part. :::{tabularcolumns} \Y{0.3}\Y{0.7} ::: :::{list-table} * - 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 {ref}`sec:energygradients.dft.doublehybrid.typical`. * - wPr2SCAN50 - Range-separated SOS-double-hybrid variant of $r^2$ SCAN with 50-100% HF exchange ::: #### 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. :::{tabularcolumns} \Y{0.3}\Y{0.7} ::: :::{list-table} * - 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) ::: #### Composite Methods :::{tabularcolumns} \Y{0.3}\Y{0.7} ::: :::{list-table} * - 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 ::: #### Dispersion corrections See {ref}`sec:energygradients.dft.vdw.typical` and {ref}`sec:model.dft.d3.detailed` for details. :::{list-table} * - 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) ::: #### Non-local correlation See {ref}`sec:model.dft.nl.detailed` for details. :::{list-table} * - NL - Does a post-SCF correction on the energy only * - SCNL - Fully self-consistent approach, adding the VV10 correlation to the KS Hamiltonian ::: (sec:basissets.structure)= ## Basis Sets ### 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 {ref}`sec:basisset.detailed`). Effective core potentials and their use are described in section {ref}`sec:basissets.ecps.structure`. #### Pople-style basis sets :::{list-table} * - 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:* :::{list-table} * - \* 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:* :::{list-table} * - $+$ 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) ::: #### 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**. :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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. ::: #### Older ("def") Ahlrichs basis sets ECP basis sets for elements **Fr-Lr**. This basis set automatically employs the original def-ECP. :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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{cite}`Zheng:2010iz`. ::: *All-electron basis sets for elements **H-Kr***: :::{list-table} * - 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`. ::: #### Diffuse def2 basis sets :::{list-table} * - *Minimally augmented def2 basis sets*: - Augmented def2 basis sets by diffuse s and p functions according to Truhlar{cite}`Zheng:2010iz`. 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.{cite}`Rappoport:2010kr,Rappoport:2021ln` * - 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 ::: #### 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.{cite}`Weigend2010-dhf-XVP` 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**. :::{list-table} * - 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 ::: (sec:rel.basissets.structure)= #### 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. :::{list-table} * - 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:* :::{list-table} * - 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.{cite}`Weigend2017-x2c-XVP` The "-s" variants, e.g. "def2-TZVPall-s", are augmented with additional tight functions for NMR shielding calculations.{cite}`Weigend2019-x2c-XVP-s` 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***). :::{list-table} * - 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 ::: (sec:sarc.basissets.structure)= #### SARC basis sets {cite}`Pantazis2008,Buehl2008,Pantazis2009,Pantazis2011,Pantazis2012,Rolfes2020` Segmented all-electron relativistically contracted basis sets for use with the DKH2 and ZORA Hamiltonians. Available for elements beyond Krypton. :::{list-table} * - 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.* ::: #### SARC2 basis sets for the lanthanides {cite}`aravenaSARC2` SARC basis sets of valence quadruple-zeta quality for lanthanides, with NEVPT2-optimized (3g2h) polarization functions. Suitable for accurate calculations using correlated wavefunction methods. :::{list-table} * - 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. ::: #### Jensen basis sets :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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 ::: #### Lehtolas hydrogenic Gaussian basis sets {cite}`lehtola2020hgbs` :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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:* :::{list-table} * - AHGBS-$m$ - ($m=$ 5, 7, 9) Variants augmented by diffuse functions * - AHGBSP$n$-$m$ - ($n=$ 1, 2, 3; $m=$ 5, 7, 9) ::: #### Sapporo basis sets :::{tabularcolumns} \Y{0.30}\Y{0.70} ::: :::{list-table} * - 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) ::: #### Correlation-consistent basis sets :::{list-table} * - 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 ::: #### Partially augmented correlation-consistent basis sets {cite}`papajak2011` :::{list-table} * - 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 ::: #### DKH versions of correlation-consistent basis sets :::{tabularcolumns} \Y{0.25}\Y{0.75} ::: :::{list-table} * - 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 ::: #### ECP-based versions of correlation-consistent basis sets :::{tabularcolumns} \Y{0.25}\Y{0.75} ::: :::{list-table} * - 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 ::: #### F12 and F12-CABS basis sets :::{tabularcolumns} \Y{0.30}\Y{0.70} ::: :::{list-table} * - 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) ::: #### Atomic Natural Orbital basis sets :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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:* :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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 - ::: #### Miscellaneous and specialized basis sets :::{tabularcolumns} \Y{0.25}\Y{0.75} ::: :::{list-table} * - 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 {numref}`tab:minix`). * - vDZP - Molecule-optimized polarized valence double-$\zeta$ basis set by Grimme et al. designed for $\omega$B97X-3c{cite}`grimme2022wb97x3c`. * - 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. ::: ### Auxiliary basis sets Auxiliary basis sets for the RI-J and RI-MP2 approximations can also be specified directly in the simple input: #### Auxiliary basis sets for Coulomb fitting :::{tabularcolumns} \Y{0.15}\Y{0.85} ::: :::{list-table} * - 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. ::: #### 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. :::{tabularcolumns} \Y{0.20}\Y{0.80} ::: :::{list-table} * - 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 ::: #### Auxiliary basis sets for correlation calculations :::{tabularcolumns} \Y{0.30}\Y{0.70} ::: :::{list-table} * - 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 {ref}`sec:basisset.autoaux.detailed` 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 {ref}`sec:basisset.builtin.detailed`). ::: ### 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: ```orca ! 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. ```orca ! 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 {cite}`Pantazis2008,Buehl2008,Pantazis2009,Pantazis2011,Pantazis2012,Rolfes2020`. 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 ({ref}`sec:basisset.autoaux.detailed`) can be employed to create auxiliary basis sets. ```orca ! PBE DKH SARC-DKH-TZVP SARC/J ... ``` Specifically for wavefunction-based calculations of lanthanide systems we recommend the more heavily polarized SARC2 basis sets {cite}`aravenaSARC2`. 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.{cite}`Weigend2017-x2c-XVP,Weigend2019-x2c-XVP-s` The matching AuxJ basis set is "x2c/J" and AutoAux can be used as well. (sec:basissets.ecps.structure)= ### 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) {cite}`hay1985chem` and Stuttgart--Dresden (SD) {cite}`fuentealba1982chem,szentpaly1982chem,fuentealba1983phys,stoll1984chem,fuentealba1985phys,dolg1987chem,igel1988mol,dolg1989chem,schwerdtfeger1989chem,dolg1989theor,andrae1990theor,kaupp1991chem,kuechle1991mol,dolg1991chem,dolg1992chem,bergner1993mol,dolg1993phys,dolg1993theor,haeussermann1993mol,kuechle1994chem,nicklass1995chem,leininger1996chem,leininger1996chemlett,leininger1997chem,schautz1998theor,wang1998theor,metz2000chem,metz2000theor,martin2001chem,cao2001chem,stoll2002comput,cao2002molec,peterson2003chem,petersonEtAl2003chem,figgen2005chem,lim2005chem,peterson2005theor,yang2005theor,lim2006chem,peterson2006phys,peterson2007chem,moritz2007theor,moritz2008theor,huelsen2009theor,figgen2009chem,weigand2009theor` 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.{cite}`flores2006comput`. A selection of ECP parameters and associated basis sets is directly accessible in ORCA through the internal ECP library (see {numref}`table:ECP_keywords` for a listing of keywords). (table:ECP_keywords)= :::{flat-table} Overview of library keywords for ECPs and associated basis sets available in ORCA. :header-rows: 1 * - ECP keyword - Core size[^1] - Elements - Valence basis sets * - - - {cspan}`1` *Recommended* * - {rspan}`1` def-ECP - 78 - Fr--Ra - {rspan}`1` Karlsruhe basis sets: def-TZVP, ma-def-TZVP * - 60 - Ac--Lr * - {rspan}`3` def2-ECP - 28 - Rb--Xe - {rspan}`3` 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 * - {rspan}`5` SK-MCDHF-RSC - 10 - Ca, Cu--Kr - {rspan}`5` 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 * - {rspan}`7` HayWadt[^2] - 10 - Na--Cu - {rspan}`7` 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 * - {rspan}`2` dhf-ECP - 28 - Rb--Xe - {rspan}`2` dhf-type Karlsruhe basis sets: dhf-SVP, dhf-TZVP, etc. * - 46 - Cs--Ba * - 60 - Hf--Rn, U * - {rspan}`5` vDZP-ECP - 2 - B--Mg - {rspan}`5` 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 * - - - {cspan}`1` *Legacy definitions* * - {rspan}`4` def2-SD - 28,MWB - Rb--Cd - {rspan}`4` * - 28,MDF[^3] - In--Xe * - 46,MWB - Cs--La * - 60,MWB - Hf--Pt * - 60,MDF[^4] - Au--Rn * - {rspan}`7` def-SD - 28,MWB - Rb--Cd - {rspan}`7` * - 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 * - {rspan}`13` SDD - 2,SDF - Li, Be - {rspan}`13` * - 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 * - {rspan}`7` LANL1 - 10 - Na--Ar - {rspan}`7` * - 18 - K--Zn * - 28 - Ga--Kr * - 36 - Rb--Cd * - 46 - In--Xe * - 54 - Cs--La * - 68 - Hf--Tl * - 78 - Pb, Bi * - {rspan}`3` LANL2 - 10 - K--Cu - {rspan}`3` * - 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 {numref}`table:basisset.availability.detailed`. ::: 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 ({ref}`sec:basisset.ecps.detailed`). 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 ```orca ! 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. (sec:numericalintegration.structure)= ## 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. {cite}`Helmich-Paris2021a`. 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 {ref}`sec:numint.detailed` 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. (sec:input.order.structure)= ## 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: ```orca ! 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: ```orca ! UKS BLYP def2-SVP %method SpecialGridAtoms 28, 29, 27 SpecialGridIntacc 8, 8, 8 end ``` (sec:symmetry.structure)= ## 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. ### 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: ```orca %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: ```{literalinclude} ../orca_working_input/C03S03_017.inp :language: orca ``` 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$_h$. ```{literalinclude} ../orca_working_input/C03S03_018.inp :language: orca ``` 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 {numref}`fig:symthresh`): $$d_{\rm min}=a-2t=3.17\:{\rm a. u.}\leq d\leq d_{\rm max}=a+2t=5.17\:{\rm a. u.}$$ 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. (fig:symthresh)= ```{figure} ../images/symthresh.png 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 $d_{\rm max}-d_{\rm min}=4t$. ``` (sec:geomopt_using_sym)= ### 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. (sec:default_alignment)= ### 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: 1. 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 $C_{\infty v}$. 2. 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 $K_h$. 3. For point group $C_s$, the mirror plane will become the $xy$ plane. 4. For point groups $C_{nv}$ $(n\ge 2)$, one of the vertical mirror planes will become the $xz$ plane. 5. 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. 6. For point groups $D_2$, $D_{2h}$, $T$, and $T_h$, the three mutually orthogonal $C_2$ axes will become the coordinate axes. 7. 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. 8. 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. 9. 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. {numref}`table:subgroups` 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:subgroups)= :::{list-table} Point groups and corresponding subgroups suitable for electronic-structure calculations. :header-rows: 3 * - 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 - $D_{2h}$ - ::: ### Irreducible representations of $D_{2h}$ and subgroups {numref}`table:species_table_c2v`, {numref}`table:species_table_d2`, and {numref}`table:species_table_d2h` 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 {cite}`mulliken1955sym` are followed. This approach is in line with the recommendations by the IUPAC {cite}`schutte1997sym`. (table:species_table_c2v)= :::{list-table} Species and species product table of point group $C_{2v}$. The species table for $C_{2v}$ corresponds to Table III in {cite}`mulliken1955sym`. 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:species_table_d2)= :::{list-table} 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 {numref}`table:species_table_d2h`). * - $\begin{array}{@{}c@{\hspace{10mm}}c@{}} \begin{array}{|l|cccc|}\hline D_2 & E & C_2(z) & C_2(y) & C_2(x) \\\hline A & +1 & +1 & +1 & +1 \\ B_1 & +1 & +1 & -1 & -1 \\ B_2 & +1 & -1 & +1 & -1 \\ B_3 & +1 & -1 & -1 & +1 \\\hline \end{array} & \begin{array}{|c|cccc|}\hline \times & A & B_1 & B_2 & B_3 \\\hline A & A & B_1 & B_2 & B_3 \\ B_1 & B_1 & A & B_3 & B_2 \\ B_2 & B_2 & B_3 & A & B_1 \\ B_3 & B_3 & B_2 & B_1 & A \\\hline \end{array} \end{array}$ ::: (table:species_table_d2h)= :::{list-table} Species and species product table of point group $D_{2h}$. The species table for $D_{2h}$ corresponds to Table IV in {cite}`mulliken1955sym`. * - $\begin{array}{@{}c@{}} \begin{array}{|l|cccccccc|}\hline D_{2h} & E & C_2(z) & C_2(y) & C_2(x) & i & \sigma(xy) & \sigma(xz) & \sigma(yz) \\\hline A_g & +1 & +1 & +1 & +1 & +1 & +1 & +1 & +1 \\ B_{1g} & +1 & +1 & -1 & -1 & +1 & +1 & -1 & -1 \\ B_{2g} & +1 & -1 & +1 & -1 & +1 & -1 & +1 & -1 \\ B_{3g} & +1 & -1 & -1 & +1 & +1 & -1 & -1 & +1 \\ A_u & +1 & +1 & +1 & +1 & -1 & -1 & -1 & -1 \\ B_{1u} & +1 & +1 & -1 & -1 & -1 & -1 & +1 & +1 \\ B_{2u} & +1 & -1 & +1 & -1 & -1 & +1 & -1 & +1 \\ B_{3u} & +1 & -1 & -1 & +1 & -1 & +1 & +1 & -1 \\\hline \end{array} \\[3mm] \begin{array}{|c|cccccccc|}\hline \times & A_g & B_{1g} & B_{2g} & B_{3g} & A_u & B_{1u} & B_{2u} & B_{3u} \\\hline A_g & A_g & B_{1g} & B_{2g} & B_{3g} & A_u & B_{1u} & B_{2u} & B_{3u} \\ B_{1g} & B_{1g} & A_g & B_{3g} & B_{2g} & B_{1u} & A_u & B_{3u} & B_{2u} \\ B_{2g} & B_{2g} & B_{3g} & A_g & B_{1g} & B_{2u} & B_{3u} & A_u & B_{1u} \\ B_{3g} & B_{3g} & B_{2g} & B_{1g} & A_g & B_{3u} & B_{2u} & B_{1u} & A_u \\ A_u & A_u & B_{1u} & B_{2u} & B_{3u} & A_g & B_{1g} & B_{2g} & B_{3g} \\ B_{1u} & B_{1u} & A_u & B_{3u} & B_{2u} & B_{1g} & A_g & B_{3g} & B_{2u} \\ B_{2u} & B_{2u} & B_{3u} & A_u & B_{1u} & B_{2g} & B_{3g} & A_g & B_{1u} \\ B_{3u} & B_{3u} & B_{2u} & B_{1u} & A_u & B_{3g} & B_{2g} & B_{1g} & A_g \\\hline \end{array} \end{array}$ ::: ### Options available in the `%Symmetry` input block {numref}`table:symmetry_block_options` 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. :::{tabularcolumns} \Y{0.2}\Y{0.1}\Y{0.15}\Y{0.55} ::: (table:symmetry_block_options)= :::{list-table} List of options in the `%Symmetry` (`%Sym`) input block :header-rows: 1 :class: longtable * - 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 {numref}`sec:default_alignment`. 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. ::: (sec:newjob.structure)= ## 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. ```{literalinclude} ../orca_working_input/C03S04_018.inp :language: orca ``` 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. ### 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.). ```orca %base "job1" ``` [^1]: Where applicable, reference method and data are given (S: single-valence-electron ion; M: neutral atom; HF: Hartree-Fock; WB: quasi-relativistic; DF: relativistic). [^2]: Corresponds to LANL2 and to LANL1 where LANL2 is unavailable. [^3]: I: OLD-SD(28,MDF) for compatibility with TURBOMOLE. [^4]: Au, Hg: OLD-SD(60,MDF) for compatibility with TURBOMOLE. [^5]: In the very special case that the Z matrix contains no atoms with mass, the geometric center will be used instead. [^6]: A center of inversion is denoted $i$. "yes" indicates the existence of a *unique* vertex that remains invariant to all symmetry operations of the point group. [^7]: This column indicates whether the given point group may be the *full* point group of a planar molecule. [^8]: This column contains the elements (axes or planes) of the coordinate system that coincide with the symmetry elements of the reduced point group (the largest common subgroup of the full point group and $D_{2h}$) by *default*. If the full point group contains a unique principle axis of symmetry (with the highest number of positions), this axis is presumed to coincide with the $z$ axis.