Tight-binding calculation of electronic and elastic properties of Ge

By accurately fitting the tight-binding (TB) parameters to ab-initio band s tructures from different tetrahedral volumes, the TB parameters have been a djusted for germanium. The model has short-range radial form similar to the tight-binding Hamiltonian of Goodwin, Skinner, and Pettifor. However, the properties of the higher-coordinated metallic structures are veil described by the model in addition to those of the lower-coordinated covalent struct ures. This one reproduces accurately the band structures of germanium polyt ypes (cubic diamond (cd), hexagonal diamond (hd), body-centered-tetragonal (beta-Sn), simple cubic (s.c.), body-centered-cubic (b.c.c.), simple hexago nal (s.h.), face-centered-cubic (f.c.c.), and compact-hexagonal (h.c.p.)) a nd gives a good description of the elastic constants for germanium in the d iamond structure.