Polyamorphic transformation of silicon in first-principles molecular-dynamics simulation

Isothermal-isobaric first-principles molecular-dynamics simulations were performed to investigate polyamorphic transformations of silicon. By pressurizing a low-density amorphous form of silicon (normal amorphous silicon with tetrahedral coordination), a new high-density amorphous form that has a strong resemblance to high-density amorphous water is obtained. It is found that the high-density amorphous form is reversely transformed to the low-density amorphous form by decompression and heating. The present simulations have revealed remarkable similarities between silicon and water, which is definitely of use to understand phase relations of polyamorphs of tetrahedrally coordinated substances.