The electronic structure and Fermi surface of molybdenum disilicide has been calculated using local-density functional theory (LDA) and the linear muffin-tin orbital method (LMTO). The energy bands are analyzed in detail for their orbital character. Our explanation for the presence of a pseudogap after the seventh band is that the two Si s bands lie low and that there are five Mo d-Si p pair bands. The configuration is approximately Mo 4d5 Si2 3s2/3p2.5. An explanation in terms of directed bond-orbitals was not achieved. The calculated angular dependence of the extremal Fermi surface cross-section areas are in good qualitative agreement with de Haas-van Alphen (dHvA) measurements. However, in order to obtain quantitative agreement, the Mo dx(2-y(2)) orbital energy has to be shifted upwards by 0.41 eV and the Mo dxy energy downwards by 0.20 eV. This deficiency is ascribed to the use of a local exchange-correlation potential.
 

Physica B, 204 65-82, 1995.