Quantum mechanical calculation of inelastic scattering of an atom by a large anharmonic cluster: Application to He+Ar13

Abstract

An approximate quantum mechanical method is proposed for the calculation of inelastic scattering of an atom from a large anharmonic cluster or molecule. The method is based on: (a) computing the vibrational states of the cluster (or molecule) in the vibrational self-consistent field approximation; (b) treating the scattering of the atom to a first approximation as taking place from a vibrationally frozen cluster; (c) obtaining inelastic transitions by a distorted wave approximation, where the coupling is the vibrationally dependent part of the atom/cluster potential. Computationally convenient expressions are worked out. The method is applied to He scattering from Ar13 and the results are compared to experimental data for size-dispersed clusters. Good qualitative agreement is found. The merits of the proposed method compared with alternative approaches are discussed. © 1998 American Institute of Physics.