Unpaired forces in the study of lattice dynamics of thorium

Abstract

A phenomenological model that considers interaction between ions in terms of two-body (central) and three-body (unpaired) forces and evaluates the effect of electron–ion interaction through a screened coulomb potential is developed for studying the lattice dynamics of thorium. The model satisfies the symmetry requirement of a lattice and fulfils the condition of invariance under rigid body rotation. Computed phonon dispersion relations and (θD – T) curve for thorium are in reasonably good agreement with the corresponding experimental data.