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The program ORCA is a modern electronic structure program package written by F. Neese, with contributions from Ute Becker, Dmytro Bykov, Dmitry Ganyushin, Andreas Hansen, Robert Izsak, Dimitrios G. Liakos, Christian Kollmar, Simone Kossmann, Dimitrios A. Pantazis, Taras Petrenko, Christoph Reimann, Christoph Riplinger, Michael Roemelt, Barbara Sandhöfer, Igor Schapiro, Kantharuban Sivalingam, Frank Wennmohs, Boris Wezisla and contributions from our collaborators: Mihály Kállay, Stefan Grimme, Edward Valeev. The binaries of ORCA are available free of charge for academic users for a variety of platforms.

ORCA is a flexible, efficient and easy-to-use general purpose tool for quantum chemistry with specific emphasis on spectroscopic properties of open-shell molecules. It features a wide variety of standard quantum chemical methods ranging from semiempirical methods to DFT to single- and multireference correlated ab initio methods. It can also treat environmental and relativistic effects.

Due to the user-friendly style, ORCA is considered to be a helpful tool not only for computational chemists, but also for chemists, physicists and biologists that are interested in developing the full information content of their experimental data with help of calculations.

How to use

New Features

  • SCF and infrastructure
    • New COSX: new grids, new analytic integrals, more accurate derivatives
    • New and robust second order converger for SCF (UHF and RHF) and automatic scheme to invoke it
    • New SHARK integral package making maximal use of BLAS level 3 operations : RHF/UHF/ROHF/CASSCF, 4-center integrals, RI integrals, better integral digestion, CP-SCF, TD-DFT, Hessian, General contraction, Range separation
    • GIAO-SOMF integrals
    • Shared memory storage for matrices and matrix containers in SCF and CP-SCF
    • Improved consistency and efficiency of the CP-SCF solvers
    • Massive improvements in Compound job functionality.
    • Massive improvement in property file content
    • Library of compound methods
    • Extrapolation for ma basis sets
    • New SARC ZORA/DKH basis sets for Rb-Xe
    • Added partially augmented (jul-, jun-, may-, apr-) Dunning basis sets
    • New symmetry handler
    • General interface out of ORCA (orbitals, integrals)
  • Geometry optimisation and transition states, Hessian
    • Multiple improvements in NEB (Flat-NEB-TS, combination with TD-DFT)
    • Conical intersection optimisation
    • Meta-GGA Hessian implementation
    • Redesign of external optimiser option
  • Properties
    • VPT2 vibrationally averaged NMR shieldings and EPR hyperfine coupling constants
    • NBO chemical shielding analysis
    • Local orbital decomposition of NMR chemical shifts
    • Improved efficiency of NMR indirect spin-spin couplings
    • Dobson's gauge-invariant ansatz for tau in meta-GGA NMR shielding and g-tensor calculations
    • 2 shell AILFT
    • ORCA LFT module for multiplet type XAS calculations
    • Exact transition moments throughout the program
    • Interface to the ANISO program developed by Liviu Ungur and coworkers
    • Local hyperfine analysis with DKH and picture change
    • Simulation of simple NMR spectra, plotting of shielding- and polarisability tensors via .cube files (orca_plot)
    • Gauge correction to hyperfine coupling tensors using effective nuclear charges
    • FMO population analysis
  • Embedding, QM-MM, Multiscale/Multilevel
    • QM/QM2 and QM/QM2/MM implementation for large systems and biomolecules
    • IONIC-CRYSTAL-QMMM for ionic crystals
    • MOL-CRYSTAL-QMMM for molecular crystals
    • AMBER conversion tool
    • Conversion from openff toolkit
    • Improved efficiency of point charge gradient
  • MP2
    • UHF RI-MP2 & DHDF second derivative properties (magnetic & electric)
    • RI-MP2 S^2
  • CCSD(T)
    • CPCM implementation in various variants
    • Correct 4th order terms in case of non-HF references
  • Multi-reference
    • Massive investments into ICE: CSF, CFG, DET, Parallelisation
    • Fully internally contracted multireference coupled cluster (FIC-MRCC)
    • CASPT2-K (CASPT2 with revised zeroth order Hamiltonian) and alternative to CASPT2 with IPEA shifts
    • Reformulated canonical CASPT2 and CASPT-K avoiding the fourth order reduced density matrices
    • Reformulated canonical NEVPT2 avoiding fourth order reduced density matrices
    • DLPNO-NEVPT2-F12
    • NEVPT2 cumulant approximation (to be used with caution)
    • Imaginary shifts for the FIC-NEVPT2
    • AILFT with DCD-CAS(2) and (H)QD-NEVPT2
    • Abelian point group symmetry in MC-RPA
    • XES spectra with CASCI
    • Gauge correction for effective nuclear charge SOC contributions to the HFC tensor at CASSCF/QDPT and DCD-CAS(2) level
    • EPR parameters at the (H)QD-NEVPT2 level
    • Access to the ANISO software by Liviu Ungur and coworkers
    • Effective Hamiltonian treatment of hyperfine A-tensors at the CASSCF/QDPT and DCD-CAS(2) level
    • Susceptibility tensors at non-zero user-defined magnetic fields
  • Local Correlation
    • RHF DLPNO-MP2 and DHDFT NMR shielding and dipole polarizability
    • Multiple major performance improvements in DLPNO-STEOM-CCSD
    • Transient absorption spectra with DLPNO-STEOM-CCSD, core excitations, IP/EA, densities
    • Multi-Level DLPNO-STEOM-IP/EA
    • Multi-Level DLPNO-MP2 (energy, gradient, response)
    • Open shell and closed shell HFLD method
    • Open shell multi-level DLPNO-CCSD(T) implementation
    • PNO extrapolation scheme to reach the PNO limit
    • Open shell DLPNO-CCSD(T)-F12
    • DLPNO-CCSD-F12 code optimisations
    • DLPNO- tailored CC
  • AutoCI
    • Massive investments in infrastructure
    • IC MRCC methods vastly improved
    • RHF/UHF CID/CISD/CEPA(0) 1-body density matrix
  • DFT
    • Gradient VV10 , VV10 GIAO-NMR
    • Update of LibXC to 5.1.0
    • LibXC support extended to range-separated and double-hybrid functionals, as well as TD-DFT gradients
    • Added parameters for B97M-D4, oB97X-D4, oB97M-D4
    • The PBE-QIDH and PBE0-DH global double hybrids
    • Range-separated hybrid LC-PBE, and the range-separated double hybrids RSX-QIDH and RSX-0DH
    • Functionality to build user-defined range-separated functionals with short-range PBE exchange
    • New range-separated double hybrids optimized for excited states: oB88PP86, oPBEPP86
    • New global double hybrids with spin-component -and opposite scaling optimized for excited states: SCS/SOS-B2PLYP21, SCS-PBE-QIDH, SOS-PBE-QIDH, SCS-B2GP-PLYP21, SOS-B2GP-PLYP21
    • New range-separated double hybrids with spin-component -and opposite scaling optimized for excited states: SCS/SOS-oB2PLYP, SCS-o-PLYP, SOS-oB2GP-PLYP, SCS-RSX-QIDH, SOS-RSX-QIDH, SCS-oB88PP86, SOS-wB88PP86, SCS-oPBEPP86, and SOS-wPBEPP86
  • Solvation
    • Analytical Hessian for the Gaussian Charge Scheme (vdW-type surface)
    • Canonical and DLPNO Coupled cluster CPCM implementation
    • Parametrisation of the free energy of solvation for the Gaussian charge scheme for organic solutes
    • More efficient potential integrals and integral derivatives
  • TD-DFT & photochemistry
    • Non-adiabatic coupling matrix elements in TD-DFT
    • LR-CPCM implementation excitation energy and gradients.
    • Collinear spin flip TD-DFT and CIS with gradient
    • Population analysis for CIS/TD-DFT
    • Spin-component and spin-opposite scaling techniques for CIS(D) and time-dependent double hybrids
    • Singlet-Triplet excitations with CIS(D), SCS/SOS-CIS(D) and time-dependent double hybrids (see list of new DFT methods above)
    • Improved infrastructure and performance
  • Molecular Dynamics Simulation
    • Additional Metadynamics module with many features and options
    • Two additional modern and powerful thermostats
    • Harmonic and Gaussian restraints for all Colvars definable
    • Thermodynamic integration possible through instantaneous printing of average force on constraints and restraints
    • Ramp possible as target value for constraints and restraints
    • Option to fix system center of mass during MD run
    • Additional printout

To use ORCA, load the orca module with the command

$ module load orca/5.0.0

For more details on using modules see our software applications guide.

#PBS -l mem=48gb
#PBS -l ncpus=24
#PBS -l jobfs=100gb
#PBS -l walltime=30:00
#PBS -l software=orca
#PBS -l wd
# Load module, always specify version number.
module load orca/5.0.0
# Must include `#PBS -l storage=scratch/ab12+gdata/yz98` if the job
# needs access to `/scratch/ab12/` and `/g/data/yz98/`
$ORCA_PATH/orca MyJob.inp >& MyJob.out

MyJob.inp is an ASCII input file. The job produces at least MyJob.out and MyJob.gbw. The latter contains a binary summary of geometry, basis sets and orbitals.

To run in parallel you need the %pal block in your input deck.

If your job is failed with an error like

rcache.c:896 UCX ERROR failed to insert region 0x37bdc320 [0x1517ace43180..0x151769af8ac0]: Invalid parameter

please modify your job script like the following way to fix the issue:

export OMPI_MCA_coll_hcoll_enable=0
$ORCA_PATH/orca MyJob.inp >& MyJob.out


The ORCA forum provides many useful resources such as Discussion Forum, FAQs and publications.

Authors: Yue Sun, Rika Kobayashi, Andrey Bliznyuk, Mohsin Ali
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