Calculo de Parámetros Electrónicos Para el Grafito Bernal

Abstract

Using ab-initio calculation, we have computed different electronic parameters associated with the transport coefficients of graphite Bernal. Software CRYSTAL 1 was used with a Pople standard STO-21G* basis set. Different hamiltonians were tested, choosing a restricted Hartree-Fock one, because it generated the best qualitative results. All graphites studied present a valence bandwidth near 0.60 a.u., in agreement with the literature. In hexagonal Bernal graphite the splitting of the valence Π band was accentuated, and E F =-0.00140 a.u. The surface Fermi is located around the HKH edge of the first Brillouin zone. In general such surfaces present a central electron orbit of maximal size in the plane, which diminish in size when the z component of the k r vector moves in KH direction. Integrating on the surface Fermi calculates the time relaxation parallel and the time relaxation perpendicular and finally we evaluate the parallel and perpendicular resistivity.