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QCMP038. 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
Converted by K. J. Tupper, QCPE 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. This software differs from QCPE 339 in that no output is written to the screen as in the original program, and two files, INPUT and OUTPUT, are opened for I/O of data. Thus, a data file must be named INPUT in order to be read. This may be changed by the user to suit his individual needs by changing the statement: OPEN(5,FILE='INPUT',STATUS='OLD') Also note that the output file is given a status of NEW, so all existing files of this name will be deleted by executing this program. The name of the output file may also be changed by the user by changing the "OPEN(6, " statement. Data which the user does not want written to the OUTPUT file may be written to the screen by substituting a ' * ' for the number '6' in the appropriate WRITE statements. The software package includes a complete version of QCPE 339 as well as the individual subroutines. Sample input and the resulting output are provided, as is the executable program QCP339.EXE which was used to generate the output. The software was compiled using Microsoft FORTRAN-77, version 3.2, using an 8087 coprocessor. The data for cis and trans (NO)2 are not included in the INPUT data file but have been included in the file CISTRANS.DAT. FORTRAN 77 (Microsoft FORTRAN) Lines of Code: 624 |