Calculation of structural pressure-induced phase transitions for magnesium using a local, first principles pseudopotential

A first principles, local pseudopotential is constructed from electronic densities which are calculated using the Hohenberg, Kohn and Sham formalism. With this pseudopotential the interionic potential is calculated for each value of compressed volume (which is taken using variations on the electronic density parameter, rs). From this potential, the corresponding phonon spectrum is obtained. The volume variation of the total energy for magnesium is calculated considering three possible structures: hexagonal close packed (hcp), face centered cubic (fcc), and body centered cubic (bcc). Two possible transitions at room temperature are predicted. The first one corresponds to a volume change of 39.7% (for a pressure of approximately 44.6 GPa). The second corresponds to a volume change of 80% (for a pressure of 1260 GPa approximately). The first transition is from hcp to bcc and it has been reported experimentally at about the same pressure. The second possible transition could occur from bcc to fcc and has not been reported experimentally yet.