Phase diagram and thermodynamic properties of solid magnesium in the quasiharmonic approximation

Using a family of volume-dependent interatomic pair potentials derived from first principles, we calculate phonon properties and thermodynamic functions in the quasiharmonic approximation for the hcp and bcc phases of Mg over a wide range of volume and temperature. At atmospheric pressure, the calculated hcp phonon-dispersion curves and thermodynamic properties agree well with experiment. The pressure dependence of the Raman-active transverse-optical phonon mode also agrees well with very recent measurements. At high pressure, the temperature dependence of the hcp-bcc phase line is predicted, with values of the transition pressure ranging from 52 GPa at zero temperature to about 28 GPa at 1000 K.