Nonlinear Phenomena in Complex Systems, 2000, Vol.3, No.4, pp.376--379

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

2000, Volume 3, Number 4, pp.376--379

Energy Level Statistics in a Molecular System with Three Degrees of Freedom: HCN/HNC
Luis Seidel, Rosa M. Benito, and F. Borondo

Calculations of wavefunctions and energy levels for the vibrational dynamics of the isomerizing molecule HCN/HNC in Jacobi coordinates for three degrees of freedom are carried out, using a recent ab initio potential energy surface. 800 energy levels have been converged using a DVR method (Discrete Variable Representation) that is well suited for large amplitude motions and highly excited vibrational levels. The classical dynamics of the system has been studied for a 2-D model and shows a mixed phase space structure with regular and chaotic regions. We have also carried out an statistical study of the energy level distribution. We have calculated the cumulative probability distribution of the level spacings W(S). This function has been fitted to a Brody distribution, which is intermediate between the well-known Poisson and Wigner distributions.
Key words: quantum chaos, level statistics, DVR method

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