CALCULATION OF THE GROUND-STATE PROPERTIES OF DIAMOND AND CUBIC BORON-NITRIDE

Using the modified augmented plane wave method (MAPW), the ground state properties of cubic boron nitride and diamond are investigated within the framework of the local density approximation (LDA). As is common for LDA, the value of the band gap is underestimated by the one-particle excited states: Calculation of the total energy as a function of the lattice parameter yields equilibrium lattice constants within 1% of the experimental value. Furthermore, the hydrostatic bulk moduli obtained deviate from the experimental values by about 10% in the case of BN and 4% in the case of diamond. An estimate of the cohesion energy of both materials is obtained from the atomic limit within the MAPW scheme yielding improved values when compared to the difference between crystal and single atom LDA total energies.