Thermodynamics of light interstitials Contributions from delocalized particles

Abstract

This paper discusses the thermodynamic consequences of those light interstitials, notably hydrogen, which can be thermally excited to delocalized states. We give an improved model for the relative importance of the vibrational and translational contributions. The model is readily applied to finite concentrations within a mean-field approximation. Quantitative estimates are given for hydrogen in liquid and solid sodium, together with estimates for positive muons which, in most respects, behave as light hydrogen isotopes.