CALCULATION OF THE ELECTRONIC AND ELASTIC PROPERTIES OF CARBON

By accurately fitting tight-binding parameters to ab initio band struc tures from different tetrahedral volumes, tight-binding parameters hav e been developed for carbon. The model has scaling form similar to the tight-binding Hamiltonian of Xu et al. However, the properties of the higher-coordinated metallic structure are well described by the model in addition to those of the lower-coordinated covalent structures. Th is one reproduces accurately the band structures of carbon polytypes a nd gives a good description of the elastic constants for carbon in dia mond structure. Results for phonon frequencies in crystalline carbon a re also presented.