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505. SURVIB: Potential Energy and Property Surface
Fitting and Vibrational Analysis, Including
Anharmonicity, for Polyatomic Systems
by Lawrence B. Harding, Theoretical Chemistry Group, Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 and Walter C. Ermler, Department of Chemistry and Chemical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030 SURVIB performs internal coordinate least-squares fits to a variety of analytical forms, searches for equilibrium and saddle points, carries out normal mode analyses, provides power series expansions in terms of normal coordinates, calculates anharmonicity and Coriolis corrections, and calculates vibrational expectation values for polyatomic potential energy and property surfaces.1 Input is in the form of values of total energies and properties for geometric configurations of the nuclei of nonlinear polyatomic systems. The normal mode eigenvectors, as well as both the internal and normal coordinate expansion coefficients, are printed and may be saved on a disk file. This also permits the use of force constants derived from experiment or other theoretical surfaces to be used as input to the normal mode analysis and following sections.The vibrational analysis is presented in the form of harmonic and anharmonic spectroscopic constants as derived according to second- order perturbation theory. Vibrational energies and property expectation values for desired states are computed using these spectroscopic constants. _________ Reference: 1. L. B. Harding and W. C. Ermler, J. Comput. Chem., 6, 13 (1985). _________ FORTRAN 77 (VAX) Lines of Code: 7324 |