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339. NCRDWC:A Program to Determine Vibration
Frequencies and Normal Modes of Vibration
by H. L. Sellers, L. B. Sims, Lothar Schafer, and D. E. Lewis, Department of Chemistry, University of Arkansas, Fayetteville, Arkansas 72701 The potential energy for vibration of a molecule is expressed in terms of internal valence displacement coordinates. The internal coordinates which are used are bond stretching, valence angle bending, out-of- plane bending, and torsion about chemical bonds. For details, see the article by J. C. Decius in J. Chem. Phys., 17, 1315 (1949). As small displacements are involved, the potential energy is expanded in the displacements from equilibrium yielding: The program accepts a general or simple valence force field with force constants corresponding to the previously mentioned internal coordinates as described in Molecular Vibrations (New York: McGraw-Hill Book Co., 1955), pp. 54-61, by Wilson, Decius, and Cross. The program converts the potential energy matrix to one which is appropriate to mass-weighted Cartesian displacement coordinates, since this affords an efficient solution for the frequencies. FORTRAN IV (IBM 360/370) Lines of Code: 624 Recommended Citation: H. L. Sellers et al., QCPE 11, 229 (1977). |