The effect of electron correlations and finite temperatures on the electronic structure of ferromagnetic nickel

Abstract

The authors introduce a new local potential for exchange and correlation in ferromagnetic materials. Its derivation rests on a recent paper by Fritsche (1986) concerned with the alternative foundation of a one-particle theory of many-electron systems. The one-particle equations arrived at in that paper contain a 'non-local' exchange-correlation potential which in the present work is approximated by a local expression. On self-consistently solving the associated one-particle equations for nickel metal, they obtain a band structure whose exchange splitting gap of 0.39 eV is considerably closer to the experimental value (namely 0.31 eV) than those which have so far been obtained by using the familiar potential of von Barth and Hedin (1972). The magnetic moment per atom is found to be 0.53 Bohr magnetons and is in fair agreement with the experimental value. Extension of the authors' calculations to finite temperatures leads to a lowering of the magnetic moment. However, due to the neglect of spatially varying excitations they arrive at a hypothetical Curie temperature of approximately 4500 K.