Isothermal-isobaric first-principles molecular-dynamics (FPMD) simulations were performed to investigate polyamorphic transformations of silicon (Si) [PRL vol.93, 055503 (2004)].
By pressurizing a normal amorphous Si with tetrahedral coordination (low-density amorphous (LDA) form), a new high-density amorphous (HDA) form that has a strong resemblance to HDA water is obtained.
It is found that the HDA form can be also obtained through vitrification of liquid Si under pressure. Both HDA and liquid Si under pressure contain deformed tetrahedral configurations with interstitial atoms. These findings indicate that HDA Si is directly connected with liquid Si, which is of particular importance in understanding phase relations of polyamorphs of Si.
