An ab initio density functional theory study was made of the electronic band structure and electric field gradient under pressure. The band structure calculations were in agreement with previous calculations. The superconductivity was related to, and dominated by, the existence of B σ px,y-band holes at the Γ point; with a negligible contribution from Mg ions. The character of the σ-band was unchanged, even after applying pressure, although there was a shift of position and an increase in dispersion. The calculated density of states decreased with pressure which, in conjunction with the Bardeen-Cooper-Schrieffer theory, agreed with the trend in the experimental TC versus pressure data. A broad bump in TC(P) data, observed near to 9GPa, was not indicated by the present band-structure study. The EFG at the B site was nearly constant, as a function of pressure, and that of Mg changed by ~34% over the pressure-range considered. The present result indicated that the B electronic system did not change much under pressures of up to ~38GPa. This confirmed one previous study, but disagreed with another.

Electronic Structure and Electric Field Gradient in MgB2 Under Pressure - an ab initio Study. F.N.Islam, A.K.M.A.Islam, M.N.Islam: Journal of Physics - Condensed Matter, 2001, 13, 11661-7