MOLCAS

Author

Origin

Department of Theoretical Chemistry, University of Lund, Sweden.

Version

MOLCAS 7.6 & 7.4

Official Web Site

http://www.teokem.lu.se/molcas/

Brief Program Description

MOLCAS is a modular program for ab initio calculations. The major strength of the package is treating electron correlation accurately by using methods based on Multi Configurational (CASSCF) approaches and many body perturbation theory (CASPT2). Such treatments allow for accurate electronic structure calculations for molecular systems in both ground and excited states. The package is considered to be a research tool, mainly for the use of theoretical chemists.

Features in MOLCAS include:

• There is a new set of coupled cluster codes added.

• The M06 DFT functional have been implemented.

• There are added constraints in slapaf.

• New method for transition state search and reaction coordinate analysis.

• There are improvements in the capabilities of the emil input.

• It is now possible to specify the actual name of the orbital input files in modules SCF and GRID_IT.

• You can now get properties broken down by orbital contributions by setting environment variable.

A full list of features is available from the MOLCAS web site:

http://www.teokem.lu.se/molcas/

Areas of Application

• Program especially well suited for very accurate calculations where reliable treatment of dynamic electron correlation is necessary, such as in the case of chemical reactions, atmospheric chemistry and photochemistry.

• Calculation of spectroscopic properties of molecules.

• Calculation of accurate potential energy surfaces.

Implementation and Access

MOLCAS 7.6 is available on Magellan and can be accessed as in the following example:

$CHEM/runmolcas76 projname

where projname can be anything but if scratch files created in one job need to be used in a subsequent job, then projname should be the same in both cases. The command assumes that the input file is in the current directory with the name of projname.input or in a directory relative to it.

The output will be deposited in the same directory in a file whose name is generated from the input file postfixed by .out (projname.out). In some cases the program will generate a MOLDEN file automatically and deposit it in the current directory. This file can be used as input to the graphical visualizer MOLDEN, in order to examine the molecular orbitals. , in order to examine the molecular orbitals.

The program runs in serial and in parallel on Magellan.

Version 7.4 is still available and can be accessed by the $CHEM/runmolcas74 command.

Machines

Available on Magellan.

Documentation

The MOLCAS User Manual is available from the MOLCAS web site, or as a PDF file in the directories: $CHEM/doc/molcas76 for version 7.6. There is an Unix-style man page containing local implementation, accessible by typing: man runmolcas76.

Literature References

References on the general background and methods used are given in the program manual.

The recommended citation for MOLCAS is:

G. Karlström, R. Lindh, P.-Å. Malmqvist, B. O. Roos, U. Ryde, V. Veryazov, P.-O. Widmark, M. Cossi, B. Schimmelpfennig, P. Neogrady, L. Seijo, Computational Material Science, 28, 222 (2003) [10].

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