THIS INFORMATION IS OBSOLETE AND IS PROVIDED ONLY FOR ITS HISTORICAL VALUE

by H. Bernhard Schlegel, Department of Chemistry, Wayne State University, Detroit, Michigan 48202

FORCE:

FORCE is a program to calculate analytical energy gradients with respect to nuclear positions, i.e., the forces on the atoms in a molecule, for ab initio LCAO- SCF wavefunctions constructed from s- and p-type Cartesian Gaussians, and to optimize molecular geometries using these energy gradients. FORCE is designed to run as a segment or overlay of existing ab initio molecular orbital programs, particularly those of the GAUSSIAN series. The calculation of the gradients requires approximately the same length of computer time as the integral and SCF steps of the molecular orbital calculation. Geometry optimization employing the analytically calculated gradients is approximately an order of magnitude faster than methods using energy alone.

DRVEXP:

DRVEXP is a progam to calculate analytical energy gradients of ab initio LCAO-SCF wavefunctions constructed from s- and p-type Gaussians. It is designed to run as a segment or overlay of existing ab initio molecular orbital programs, particularly those of the GAUSSIAN series. The calculation of the gradient with respect to all the basis-set parameters and atom positions requires about twice as much computer time as the integral and SCF steps of the molecular orbital calculation. If only the forces on the atoms are required, as in geometry optimization, the program FORCE should be used instead.

FORTRAN IV (IBM) Lines of Code: 5400