On the Extended Forms of Phenomenological Models for the Lattice Dynamics of BCC Transition Metals

Abstract

The Sharma-Joshi and Krebs phenomenological models for the lattice dynamics of cubic metals have been extended and are applied to study the phonon dispersion curves of tungsten, a metal for whlch long range forces are also important. It has been found that, unlike extended forms of the de Launay model (Shukla and Cavalheiro 1973a) for certain cubic metals, the models studied here for b.c.c. transition metals are not always adequate. Possible reasons for the shortcomings of the results are pointed out and discussed. The role of angular forces, particularly when they are used along with a fairly good conduction electron-ion interaction term, has been examined and found to be unimportant