Structural, electronic, elastic properties and phase transitions of Mg2Si from first-principles calculations

Structural and electronic properties of Mg2Si under high pressures are investigated based on density functional theory The calculations found that Mg2Si undergoes two pressure-induced phase transitions: anti-fluorite -> anti-cotunnite -> Ni(2)ln-type. The dependence of the elastic properties on pressure in three strucures is further analyzed. The band structures show that for the anti-fluorite structure that the pressure leads to change in the energy dispersion of lowest conduction band but the energy dispers relations of the valence band top hardly be changed. This indicates that the conduction bands for the anti-fluorite structure are influenced by the pressure whereas the valence bands are not much affected.