[Logo] Centre for Molecular and Biomolecular Informatics
Radboud University Nijmegen


MOPAC 93 (the successor of MOPAC 6.0) is a general-purpose semi-empirical molecular orbital package for the study of solid state and molecular structures and reactions, written by James J.P. Stewart.

The semi-empirical hamiltonians MNDO, MINDO/3, AM1 and PM3 are used in the electronic part of the calculation to obtain molecular orbitals, the heat of formation and its derivative with respect to molecular geometry. Using these results MOPAC calculates the vibrational spectra, thermodynamic quantities, isotopic substitution effects and force constants for molecules, radicals, ions, and polymers.
For studying chemical reactions, a transition state location routine and two transition state optimizing routines are available.
The simplest description of how MOPAC works is that the user creates a data-file (extension .dat) which describes a molecular system and specifies what kind of calculations and output are desired.
The user then commands MOPAC to carry out the calculation using that data-file. The CMBI menu offers a list of input files and an overview of available queues, from which the appropriate entries are selected.
Finally, the user extracts the desired output on the system from the output files (.out and .arc files, supplementary files depending on keywords) created by MOPAC.

[MOPAC Setup Menu] MOLDEN can be used to examine the results of the calculations: it reads and displays the information from the output files, e.g., the geometry, reaction coordinates, and vibrations. If the keywords VECTORS and GRAPH had been specified, orbital coefficients can be shown as well.

SYBYL can be used to display MOPAC information if all the necessary files are present, which is most conveniently accomplished by running the job from within Sybyl. Again, for orbitals the keywords VECTORS and GRAPH can be switched on in the MOPAC Setup menu.

Dr. J.J.P. Stewart and Fujitsu Limited

Academic license through QCPE, no. 455.

A manual ($70 plus $35 shipping&handling) can be ordered through the CMBI.

A WWW course, illustrating the use of MOPAC, Gamess and Molden in `organic' applications and developed at CMBI is available via the Internet. A similar course (six days) for graduate or post-graduate students is scheduled each fall semester in the Centre's lecture room.