ORCA

Author

F. Neese, with contributions from U. Becker, F. Wennmohs, D. Ganiouchine and T. Petrenko.

Origin

Frank Neese, Max-Planck Institut für Bioanorganische Chemie, Germany.

Version

ORCA 2.6.4 and ORCA 2.5

Official Web Site

http://www.thch.uni-bonn.de/tc/orca/

Brief Program Description

ORCA is an electronic structure package that has been specially designed to calculate the spectroscopic properties of open-shell molecules including absorption and circular dichroism spectra, EPR parameters, Mossbauer parameters, NMR parameters and IR/Raman spectra. The package features a wide variety of standard quantum chemical methods ranging from semiempirical methods to DFT to correlated ab initio methods. It can also be used to treat environmental and relativistic effects.

Areas of Application

Specific methods implemented in the package include:

• Semiempirical AM1, PM3, ZINDO, NDDO, MNDO, Hartee Fock.

• DFT including a reasonably large number of exchange and correlation functionals including hybrid DFT.

• High level ab-initio methods (MP, CI, CEPA, CC) with emphasis on individually selecting multireference CI type approaches for ground- and excited-states.

• Geometry optimization in redundant internal coordinates using analytical gradient techniques for all SCF methods.

• Excited state calculations via TD-DFT and CI-singles (CIS).

• Scalar relativistic ZORA and Douglas-Kroll-Hess (DKH) approaches.

• The COSMO model is available throughout the package for continuum dielectric modelling of the environment.

• Large number of user defined point charges can be read by the program which allows to interface existing QM/MM methods.

More information about the ORCA program can be found at the website:

http://www.thch.uni-bonn.de/tc/orca/

Implementation and Access

The command $CHEM/runorca accesses and executes the computational chemistry program ORCA version 2.6.4. ORCA can only be run in serial and must be run in batch on Magellan.

Please refer to the man page for more details on the local implementation.

The previous version of the code (ORCA 2.5) can be accessed via the $CHEM/runorca25 command. Please see the runorca25 man page for more details.

Machines

Available on Magellan.

Documentation

The ORCA User Guide is available as a PDF file in the directory $CHEM/doc/orca.

There is a Unix-style man page containing information on the local implementation of ORCA, accessible by typing: man runorca.

Further information can also be found on the ORCA website:
http://www.thch.uni-bonn.de/tc/orca/

Literature References

References are listed in the ORCA User Manual.

Specialist Support

Dr Helen Tsui. Address: Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ. Tel: 020 7594 1220 Email: helen.tsui@imperial.ac.uk.

Program Restrictions and Comments

N/A