Adiabatically corrected quasiclassical model for the vibrational predissociation of van der Waals complexes Original Research Article

For a collinear model of a van der Waals complex A-BC, we present a quasiclassical adiabatically corrected theory of vibrational predissociation. The approach is based on the recovery of the quasiclassical Landau exponent from the attributes of the classical motion of the system (E.E. Nikitin and L. Pitaevskii, Phys. Rev. A 49 (1994) 695). The theory is applied to the generalized Beswick-Jortner Hamiltonian for a prototype system NeIcl and is shown to reproduce the exact level widths quite well. Approximate formulae are suggested which correct the widths, calculated within the original Beswick-Jortner theory, for the main adiabatic effects not included in the first-order perturbation treatment: stiffening of the BC oscillator, softening of the A-BC repulsive interaction, and the increase of the interaction range of A and BC with the growth of the vibrational quantum number of BC.