A new tight binding parameterization for carbon

Working within a minimal orbital sp basis set with fixed site energies and a repulsive pairwise interaction the author fits a set of hopping integrals and a repulsive pair potential to experimental graphite and diamond band structures, binding energies, lattice constants and bulk moduli, and to accurate local density functional data for the binding energies and equilibrium volumes of face centred cubic, simple cubic and beta tin phases of carbon. He finds that an approximately inverse cube form for the hopping integrals as a function of interatomic separation and an approximately inverse nine-halves power for the air potential leads to an improved fit to the data including the band structure of graphite. Both the hopping integrals and the pair potential are seen to decay more rapidly than similar parameters for silicon, reflecting the absence of nuclear screening by core electron states.