Accession Number:

ADA232891

Title:

Normal Mode Analysis of van der Waals Vibrations

Descriptive Note:

Technical rept.

Corporate Author:

COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY

Personal Author(s):

Report Date:

1991-03-07

Pagination or Media Count:

37.0

Abstract:

Two algorithms are presented for calculation of the van der Waals modes of weakly bound clusters. Both methods rely on the harmonic normal mode approximation and a chosen intermolecular potential. These calculational techniques differ specifically in the form of the force field employed one method uses the total both intra- and inter- molecular force field for the cluster and the other uses only the intermolecular force field. Both methods require rather elaborate coordinate transformation and their first and second partial derivatives these are provided in detail. The two calculations generate eigenvalues and eigenvectors that are in complete agreement with one another for a given potential. The methods insure that the van der Waals modes are calculated at the proper cluster equilibrium configuration for which all torques and forces on molecules andor atoms are effectively zero. Examples are presented for H2O2n2, ...,7, benzene clustered with water, methane, and ammonia, and a number of different intermolecular potentials. Some of the observed heterogeneous cluster van der Waals modes are reassigned in light of these new result. Author

Subject Categories:

  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE