First-Principles Investigations on Structural Transformation and Electronic Properties of BeP2N4 under High Pressure

Total energy of BeP2N4 as a function of unit cell volume was calculated for phenakite and spinel-type structures using the density function theory (DFT). According to the Brich-Murnaghan's equation of state, the bulk modulus B0 and B0=dB/dp for these two structures were obtained. The calculated results are all in good agreement with other theoretical data available in the literature, which indicate that BeP2N4 will transform from phenakite to spinel-type with increasing pressure. The results are in good agreement with experimental and other theoretical results. The energy gap slightly increases with pressure in the phenakite and spinel-type phases. The compression ratio of a/a0 and V/V0 were calculated. We find the the compression ratio of a/a0 and V/V0 of spinel structure BeP2N4 is the same that of diamond at lower 5 GPa. The BH, GH, BH/GH and E were also calculated at high pressure. By analyzing the changes of the total electronic density of states (TDOS) and the band gap under pressure, it is found that the energy band width and charge transfer for the two structures increase with increasing pressure. Moreover, the BeN, PN bond length is shortened and the electric charges are redistributed.