Determination of free energy difference between anomaly solid-liquid phase transitions of silicon using pseudo-supercritical thermodynamic path: a molecular dynamics study

Abstract

Silicon shows a very different trend while melting. Melting has remained a challenging subject from a long time. Especially, predicting the melting temperature of any solid substance still exists as a problem in many cases. Recently, various studies and new rules and set of parameters have simplified things, but its mechanism is yet to be studied properly and there does not exist any generalized concept regarding this. This work is an attempt to study the mechanism of free energy difference between solid-liquid. In order to understand the free energy difference, it is important to know the interaction potential governing the silicon system. Stillinger-Weber potential is a good model for Si atoms which takes into account two and three particle interactions. Heating and quenching processes is implemented on a system of Si atoms. Free energy gap connecting phases is estimated with the help reversible thermodynamic route. Supercritical path is constructed with the help of more than one reversible thermodynamic path. The best of my knowledge, this is first attempt to implement pseudo-supercritical reversible thermodynamic path for a system whose solid volume is higher than liquid volume at phase transition point.