Bloch electron scattering in relaxed lattices: a test on dilute alkali alloys

An investigation has been made into the scattering of Bloch electrons by Na and Rb impurities in dilute potassium alloys. The calculations are based on a muffin-tin description of the potential. The scattering object has been taken to be the impurity and its nearby environment up to three host atom shells, whether relaxed or not. Charge transfer has been accounted for within these shells. The phaseshifts of host and scattering atoms have been constructed in a standard way or have been obtained from the literature. It appears that relaxation does not influence the average lifetime very much. However, the anisotropy improves significantly when distortion is taken into account. The results show a strong sensitivity to the potential used. In K(Na) the choice of alpha =2/3 for the exchange coefficient leads to satisfactory results in contrast to those obtained when alpha =1. The results for K(Na) are better than those for K(Rb). These calculations show that it is possible to use this method as a tool to test the various possible potential constructions. The results clearly show a need for self-consistency determined potentials.