High-pressure electronic and optical properties of α-Si3N4

Based on the density functional theory, the plane-wave pseudo-potential method is performed to investigate the structural properties of alpha-Si3N4. The ground-state lattice parameters (i.e. lattice constants and cell volume) agree quite well with the experimental data. From the band structure calculation, we found that the stability of alpha-Si3N4 is due mainly to the interaction among the Si-s, Si-p and N-p states. The imaginary part of the dielectric function has a sharp peak at 8.2eV. For the real part of the dielectric function, the highest peak locates at 6.5eV. Our calculated results are in good agreement with the experimental data and previous theoretical values. Therefore, the calculated results may provide useful information for further investigations of alpha-Si3N4.