Structural properties of supercooled liquid silicon by molecular dynamics

Structural changes on supercooling liquid silicon

“…In conclusion, joint XRD measurements and AIMD simulations of liquid Si provide strong support for a reinforcement of the tetrahedral ordering as the temperature is reduced in the supercooled liquid, as evidenced by the following three trends: (1) A decrease in coordination number. (This finding confirms our previous results [6] as well as those from recent conventional MD with the Stillinger-Weber potential [9,10]). (2) Enhancement of the shoulder following the first peak of the structure factor into a clearly resolved peak.…”

“…From a theoretical point of view, it has been shown that a lowering of the coordination number with temperature in the supercooled liquid occurs even under compression [9]. This was interpreted recently as being due to the possible existence of a second low coordinated liquid phase associated with a liquid-liquid phase transition [10,11].…”

Nanometer-scale dynamics of high-temperature levitated liquids

“…In the stable liquid phase, the main peak has a shoulder on the high-Q side, which becomes resolved into a second peak as the temperature decreases into supercooled regime [37]. The main features of the diffraction patterns are successfully reproduced by ab-initio molecular dynamics calculations [35,37]. The sharpening of the shoulder, reduction in coordination number to about 5.5 and an increase in the amplitude of the maximum in the bond-angle distribution close to the tetrahedral angle, all indicate that the tetrahedral ordering is reinforced in the supercooled regime [37], supporting the conjecture of Angell and Borick.…”

“…In the crystalline phase at ambient conditions, silicon is a diamond-structured semiconductor but on melting it undergoes a semiconductor-to-metal transition accompanied by significant changes in the structure and density. The coordination number increases from 4 in the solid to about 6.5 in the liquid [35] and the liquid density is increased by about 10% [36]. In addition, the experimental structure factor S(Q) of liquid silicon shows a distinct characteristic feature around the first maximum.…”