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

An atomistic simulation based on the Buckingham potential is investigated i n order to describe the phonon behaviour in the wurtzite, zinc-blende, rock salt 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 E-2 (low) mode, in good agreement with experimental resu lts. Our calculations are extended to predict the dynamical properties of t he zinc-blende, rocksalt and NiAs phases such as the evaluation of the pres sure coefficient and the Gruneisen parameter for each mode. (C) 2001 Elsevi er Science Ltd. All rights reserved.