First-Principles Calculations on Electronic, Chemical Bonding and Optical Properties of Cubic Hf3N4

Electronic, chemical bonding and optical properties of cubic Hf3N4(c-Hf3N4) are calculated using the first-principles based on the density functional theory (DFT). The optimized lattice parameter is in good agreement with the available experimental and calculational values. Band structure shows that c-Hf3N4 has direct band gap. Densities of states (DOS) and charge densities indicate that the bonding between Hf and N is ionic. The optical properties including complex dielectric function, refractive index, extinction coefficient, absorption coefficient, and reflectivity are predicted. From the theory of crystal-field and molecular-orbital bonding, the optical transitions of c-Hf3N4 affected by the electronic structure and molecular orbital are studied. It is found that the absorptive transitions of c-Hf3N4 compound are predominantly composed of the transitions from N T(2)2p valence bands to Hf T-2 (d(xy), d(xz), d(yz)) conduction bands.