Serena Software

Mopac version 6

Mopac is a general purpose semi-empirical molecular orbital program for the study of chemical structures and reactions. It is the culmination of more than twenty years of research starting in the research group of Professor Michael J. Dewar and currently being carried on by Dr. J.J.P. Stewart. It uses semi-empirical quantum mechanical methods which are based on Hartree-Fock theory with some parameterized functions and empirically determined parameters replacing some sections of the complete HF treatment. The approximations in semiempirical theory result in more rapid single energy calculations which allows much larger structures to be studied. Mopac can use the semi-empirical Hamiltonians MNDO, MINDO/3, AM1 and PM3 to obtain molecular orbitals, heats of formation and their derivatives with respect to molecular geometry. Using these results Mopac can calculate the vibrational spectra, thermodynamic quantities, dipole moments and molecular orbitals and electron densities. Since Mopac is an quantum chemistry program it recognizes electron reorganization and thus Mopac can be used to study reaction mechanisms. This is in contrast to molecular mechanics programs which can only deal with a particular valence representation of a molecule.

The code we use in porting Mopac to the PC and Macintosh comes from QCPE (the Quantum Chemistry Program Exchange) and is program QCPE #504. Thus the code is identical to the code being used world wide, and results from a Mopac calculation can be published in the chemical literature.

Mopac is available for :