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228. MINDO/2': Geometry Optimization Program: SIMPLEX

by Michael J. S. Dewar and Patrick Student, Department of Chemistry, University of Texas, Austin, Texas 78712

The program performs geometry optimization of the MINDO/2' energy using the SIMPLEX algorithm.

This program is in FORTRAN for a CDC 6600 and uses approximately 32 Kb of core. The program now handles up to 30 atoms, 60 orbitals and 50 variables. The program requires N2 SCF evaluations where N is the number of variables to be optimized.

The sample problems and documentation with this program provide some insights into its versatility. Included are sample input for ethylene and bicyclobutane.

The bicyclobutane example is especially interesting, because its calculation contains parameters which are dependent on previously defined parameters; and this situation can be handled, in general, by the inclusion of a user-supplied subroutine which handles this problem. For bicyclobutane, the subroutine DEPVAR is included with the program.

The documentation also indicates how the systematic change in a parameter, which is defined as the reaction coordinate, can be handled in studying a reaction.

FORTRAN IV (CDC 6600) Lines of Code: 2756 Recommended Citation: M. J. S. Dewar and P. J. Student, QCPE 11, 228 (1973).



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