Superconductivity in MgB2 and TaB2: A Full-Potential Electronic Structure Comparison

We present a comparison of electronic structure of MgB2 and TaB2, the two new superconductors, as well as VB2, calculated using full-potential, density- functional-based methods in P6/mmm crystal structure. Our results, described in terms of (i) density of states (DOS), (ii) band-structure, and (iii) the DOS and the electronic charge density in a small energy window around the Fermi energy EF. In particular, the charge density around EF in MgB2 and TaB2 show striking similarity as far as the B plane is concerned. A comparison of their band-structures, coupled with l-character analysis, indicates that TaB2 has substantially more p-character than VB2 along A-L and H-A directions near EF.