Accurate variational calculations and analysis of the HOCl vibrational energy spectrum

Citation
S. Skokov et al., Accurate variational calculations and analysis of the HOCl vibrational energy spectrum, J CHEM PHYS, 109(23), 1998, pp. 10273-10283
Citations number
75
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF CHEMICAL PHYSICS
ISSN journal
00219606 → ACNP
Volume
109
Issue
23
Year of publication
1998
Pages
10273 - 10283
Database
ISI
SICI code
0021-9606(199812)109:23<10273:AVCAAO>2.0.ZU;2-S
Abstract
Large scale variational calculations for the vibrational states of HOCl are performed using a recently developed, accurate nb initio potential energy surface. Three different approaches for obtaining vibrational states are em ployed and contrasted; a truncation/recoupling scheme with direct diagonali zation, the Lanczos method, and Chebyshev iteration with filter diagonaliza tion. The complete spectrum of bound states for nonrotating HOCl is compute d and analyzed within a random matrix theory framework. This analysis indic ates almost entirely regular dynamics with only a small degree of chaos. Th e nearly regular spectral structure allows us to make assignments for the m ost significant part of the spectrum, based on analysis of coordinate expec tation values and eigenfunctions. Ground state dipole moments and dipole tr ansition probabilities are also calculated using accurate ab initio data. C omputed values are in good agreement with available experimental data. Some exact rovibrational calculations for J = 1, including Coriolis coupling, a re performed. The exact results are nearly identical with those obtained fr om the adiabatic rotation approximation and very close to those from the ce ntrifugal sudden approximation, thus indicating a very small degree of asym metry and Coriolis coupling for the HOCl molecule. (C) 1998 American Instit ute of Physics. [S0021-9606(98)00947-7].