The electronic stopping power of heavy targets

Abstract

The aim of this work is to face the challenge of describing the stopping power in heavytransition and posttransition metal solids in an extended energy range. The present study examines the stopping of hydrogen in Hf, W, Pb, and Bi. The electronic structure description of the targets requires solving the many-electron Dirac Hamiltonian. We inquire the influence of employing various relativistic approximations, and its effect on the energy loss. The theoretical model of the stopping power considers separately the valence electrons of the metal-accounted for as a free-electron gas and the bound electrons. The former are described using a nonperturbative binary screening potential or the dielectric formalism, depending on the energy regions and plasmon excitation threshold. For the later, the approach uses the dielectric formalism for each subshell by means of the shellwise local plasma approximation. We inspect the importance of accurately describing the 4f and 5d electrons, the spin?orbit split, the intra- and intershell screening among electrons, and the different quantum dielectric response functions. The present results correctly describe the stopping cross sections in comparison with the data available, the theoretical models DPASS and CasP, and the semiempirical SRIM. Based on these results, we analyze the state of art of the experimental values and suggest the need for new measurements in certain energy ranges and targets.