The Brandt-Kitagawa heavy ion model: Embedding in the homogeneous electron gas

Abstract

The ion model by Brandt and Kitagawa [Phys. Rev. B 25 (1982) 5631] has played a major role in the development of the effective charge theory for the electronic stopping of heavy ions in solids. Embedding it into the electron gas of the target leads to an enhanced screening of its bound electrons, modification of its size parameter and eventually of its effective charge. A basic, earlier calculation [T. Kaneko, Phys. Rev. A 41 (1990) 4889] overestimates the effect, but can be improved by confining the influence of the target dielectric to the region of the outermost bound electrons of the ion.