The vacancy parameters in transition metals having the body-centered cubic structure were investigated by means of electronic-structure calculations. A semi-empirical tight-binding d-band approach was proposed which showed that the position of the Fermi level, with respect to the pseudo-gap, governed the sharp variations (among a series of transition metals) of the formation energy, relaxation energy, migration energy and electronic contributions to the formation and migration entropies. The predicted trends were confirmed by first-principles calculations for the 5d body-centered cubic metals, Hf, Ta and W. These included structural relaxations within plane-wave pseudopotential computations which were performed on super-cells that contained up to 54 sites. The agreement with available experimental data was conclusive.

Electronic Structure Calculations of Vacancy Parameters in Transition Metals - Impact on the BCC Self-Diffusion Anomaly. F.Willaime, A.Satta, M.Nastar, O.Le Bacq: International Journal of Quantum Chemistry, 2000, 77[6], 927-39