"Morphing" of ab initio-based interaction potentials to spectroscopic
accuracy: Application to Cl-(H2O)
J. M. Bowman and S. S. Xantheas
Cherry L.Emerson Center for Scientific Computation
and Department of
Chemistry, Emory University, Atlanta, GA 30322, USA;
Chemical Sciences Division, Pacific Northwest National Laboratory, P.O.Box
999, MS K1-83, Richland, WA 99352, USA
Abstract:
We present anharmonic vibrational calculations for the Cl-(H2O)
cluster and their convergence with the n-mode representation
of the interaction potential. Extension of this representation up to
4-mode couplings produces results that appear to be converged to within
10 cm-1 or less relative to the exact 6-mode representation
for this system. This methodology, in conjunction with the "morphing"
technique, which is based on the scaling of the internal coordinates,
provides an effective means of fitting intermolecular potentials to
measured vibrational spectra. Application of this approach to the chloride-water
interaction produces a revision of a previously developed empirical
interaction potential that reproduces the measured fundamental and first
overtone frequencies to within an average absolute deviation of 1.75
cm-1 in the 4-mode coupling representation.
*Lecture presented at the European Molecular Liquids
Group (EMLG) Annual Meeting on the Physical Chemistry of Liquids: Novel
Approaches to the Structure, Dynamics of Liquids: Experiments, Theories,
and Simulation,Rhodes, Greece, 7-15 September 2002. Other presentations
are published in this issue, pp. 1-261.
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