Ab initio study of the high-pressure phase transition from the cubic-diamond to the beta-tin structure of Si

We have studied the high-pressure phase transition from the cubic-diamond ( cd) to the P-tin structure of silicon. This work has been performed using t he plane-wave pseudopotential approach to density-functional theory (DFT) a nd density-functional perturbation theory (DFPT) within the local-density a pproximation (LDA). We present results on the pressure dependence of ground -state properties, such as lattice-parameters, and electronic band structur e. Furthermore, the pressure dependence of the phonon-dispersion curves is shown. The calculated transition pressure and volumes are in good agreement with experimental values. In particular, our results show no softening of phonon modes near transition. Finally, our calculation of pressure-dependen t phonon-dispersion curves allows the calculation of the pressure vs. tempe rature phase diagram within the quasi-harmonic approximation. (C) 2001 Else vier Science B.V. All rights reserved.