Electronic structure and superconductivity of MgB2

Results of ab initio electronic structure calculations on the compound, MgB2, using the FPLAPW method employing GGA for the exchange-correlation energy are presented. Total energy minimization enables us to estimate the equilibrium volume, c/a ratio and the bulk modulus, all of which are in excellent agreement with experiment. We obtain the mass enhancement parameter by using our calculated, D(EF) and the experimental specific heat data. The Tc is found to be 37 K. We use a parametrized description of the cal- culated band structure to obtain the T = 0 K values of the London penetration depth and the superconducting coherence length. The penetration depth calculated by us is too small and the coherence length too large as compared to the experimentally determined values of these quantities. This indicates the limitations of a the- ory that relies only on electronic structure calculations in describing the superconducting state in this mate - rial and implies that impurity effects as well as mass renormalization effects need to be included.