Orca

Using ORCA’s DLPNO-CCSD(T) it is possible to compute binding energies, reaction energies/rates, and other properties with an accurate, robust, and parameter-free quantum chemistry method!

The DLPNO scheme reduces the computational cost of the problem, so that the calculations are affordable for systems with hundreds of atoms at a cost similar to DFT – but at much higher accuracy.

NEB-TS is our newest method to find reaction paths and transition states, starting from the structures of the reactant and product only.

It is designed to run black box, and works successfully even for multi-bond forming/breaking mechanisms. Combined with our multiscale schemes, it can even be used to study reactions inside proteins!

The RIJCOSX accelerates HF and hybrid-DFT calculations by huge factors – for some features by almost 100-fold – and it is available for all kinds of methods in ORCA.

We have all kinds of modern DFT functionals implemented: LDA, GGA, meta-GGA and double-hybrids, including recent ones such as r²SCAN and ωB97M-V.

The acceleration schemes such as DLPNO and RIJCOSX are available for the more accurate density functionals that require MP2 or HF-exchange, rendering accurate DFT calculations on large systems affordable.

Our built-in QMMM and ONIOM modules allow for multilevel calculations in systems of any size. The methods are designed for easy setup/usage and are well integrated into all other ORCA modules.

This way, all ORCA features can be used, which is particularly interesting for reactivity prediction and design in enzymes.

Our Crystal-QMMM features allow to use ORCA’s accurate methods on solids. Spectroscopic properties and band gaps can be computed for semiconductors, insulators as well as molecular crystals.

ORCA was designed from its very begining to deal with complicated electronic structures, and excited states are no exception.

We have single and multireference methods, including TD-DFT for regular and double-hybrid functionals, EOM- and STEOM-CCSD, as well as CASSCF with NEVPT2 or CASPT2. All these profit significantly from the RIJCOSX and DLPNO schemes.

The ORCA_ESD module was designed to predict more realistic, vibronically-resolved UV/Vis, Fluorescence, Phosphorescence and resonant Raman spectra.

Using the same approach it is also possible to compute photophysical rate constants for these processes. Thus, it is possible to estimate quantum yields of Fluorescence, Phosphorescence, and ISC.

ORCA provides a broad variety of highly accurate multireference methods, such as CASSCF/NEVPT2, MRCI, MRCC and even FCI

We make sure they are as easy as possible to use and included all the nice RIJCOSX and DLPNO acceleration schemes to bring down the timings.