Semiclassical description of proton stopping by atomic and molecular targets

Abstract

In recent years there has been renewed interest in semiclassical methods of modeling atomic structure and collision dynamics. A class of many-body models applied to these problems are descendants of the original work by Kirschbaum and Wilets [Phys. Rev. A 21, 834 (1980)], who used momentum dependent pseudopotentials to exclude particles from quantum mechanically forbidden regions of phase space. These methods have been used for static, ground-state calculations for increasingly complex atoms, but the calculation of collision cross sections has to date been limited to fairly simple systems. This paper will consider the dependence of collision cross-section calculations on the parameters of the Kirschbaum-Wilets semiclassical model, present a general method for calculation of proton stopping powers by atomic targets, and present results for proton stopping by atomic targets ranging from He to Ne which agree quite well with experiments over a wide range of proton energies. A simple extension of the method to multicenter molecular targets will then be discussed, illustrated by the case of proton stopping by water.