Calculation of atomic charge- moment- and current densities using McPhase, a versatile modelling suite for magnetic neutron scattering

Abstract

Information on the anisotropy of the atomic magnetic moment density can be obtained from neutron scattering. Within the dipole approximation the effect of the anisotropy is usually neglected. We show how the anisotropy of the charge-, spin-, orbital moment and current densities of an unfilled shell can be calculated. The theoretical formulae have been implemented in the McPhase software suite. We illustrate the theory for some representative examples of different magnetic ions in an idealized crystal field. Moreover, we also evaluate the various densities for some real systems.