Thermal dependence of the properties of cubic boron nitride crystal

Abstract

Lattice constant, total energy, cohesive energy, bulk modulus, speed of sound (υ), plasmon energy (Epl), valence charge distribution and energy bands of cubic boron nitride crystal have been calculated and studied as a function of temperature using self-consistent field tight binding method with complete neglect of differential overlap version 2 using 8-atom large unit cell approach. Our results illustrate that the increase of temperature leads to an increase of lattice constant, cohesive energy, and valence charge distribution at the atoms, whereas a decrease is obtained for bulk modulus, energy band widths, valence charge distribution in the intratomic distance, speed of sound, and the plasmon energy. The comparison with experimental and other theoretical results has showed an excellent agreement for the lattice constant, bulk modulus, cohesive energy, speed of sound, plasmon energy value and the valence band, whereas remarkable differences in charge distribution values, and the band gap are found. These differences are common in the results that depend on this type of calculation. Values for conduction band and speed of sound have not been found for comparison. Our relation for Epl-T fails but the υ-T relation is successful.