Superconducting properties of MgB2 from first principles

The discovery of superconductivity in MgB2, With a rather high transition temperature, has triggered a large number of theoretical and experimental investigations on important issues such as, e.g., the role of gap anisotropy over the Fermi surface (multi-gap superconductivity). We report here the results obtained in this compound using the density functional theory for superconductors, recently proposed by the authors. Without invoking any adjustable parameters, such as mu(*), we obtain the transition temperature, the gaps, and the specific heat in very good agreement with experiment. Moreover, our calculations allow for a detailed study of how the phonon-mediated attraction and Coulomb repulsion act differently on sigma and pi states, thereby stabilizing the observed superconducting phase. (c) 2007 Elsevier B.V. All rights reserved.