Pressure effect on phonon modes in gallium nitride: a molecular dynamics study

An atomistic simulation based on the Buckingham potential is investigated in order to describe the phonon behaviour in the wurtzite, zinc-blende, rocksalt and NiAs structures in gallium nitride. The obtained results show the presence of soft modes in the wurtzite structure, with a negative pressure coefficient of the E2 (low) mode, in good agreement with experimental results. Our calculations are extended to predict the dynamical properties of the zinc-blende, rocksalt and NiAs phases such as the evaluation of the pressure coefficient and the Gruneisen parameter for each mode.