Atomistic modelling of quantum diffusion in metals

Abstract

Most theories of quantum diffusion start from model Hamiltonians. The diffusion rates are calculated in terms of parameters such as an effective tunnelling frequency. Often low temperature expansions are used. In this paper we present a calculation of diffusion rates from given interatomic interactions. The approximations leading to the model description are discussed and their breakdown with increasing temperature is shown. The experimental diffusion rates for H in Nb are reproduced by a parameter free calculation.