High-pressure phases of amorphous and crystalline silicon

We study pressure-induced phase transitions in amorphous silicon and crystalline diamond silicon from Gibbs free energies considerations using ab initio total energy calculations. We predict a pressure-induced crystallization of the amorphous network at 2.5 GPa and a first order amorphous to amorphous phase transition at 9 GPa. Furthermore, we find a pressure-induced high density amorphization of crystalline diamond silicon around 15 GPa.