Static Structure of Liquid GeSe Under Pressure: Ab Initio Molecular Dynamics Simulations

Abstract

The authors have investigated the pressure dependence of the static structure of liquid GeSe based on ab initio molecular dynamics simulations. In a pressure range of about 240 GPa, there are four stages of compression process. In the first stage up to about 8 GPa, the Peierls‐type distortion, seen in the crystalline phase, is retained in the liquid phase. This Peierls‐type distortion completely dissolves during the second stage between 8 and 12 GPa. At this stage, a semiconductor–metal (SCM) transition also occurs. While the distance between Ge–Se atoms is almost unchanged in the first and second stages, it shortens with increasing pressure under further compression. The coordination number around Ge atoms is larger than that around Se atoms in the third stage up to about 40 GPa. Both the coordination numbers become the same in the fourth stage under higher pressure, where a denser liquid phase appears with the coordination number larger than eight.

Hierarchical Short- and Medium-Range Order Structures in Amorphous GexSe1–x for Selectors Applications

“…At high temperatures, the partial correlation function on Sn(q) of Ge-Se has a minimum at 1.8Å -1 together with a peak at 2.3Å -1 ; while in the case of Se-Se, the FSDP is at 1.8Å -1 . These values are close to those obtained both by experiment and computer simulation studies on liquid GeSe 23,24,50 . Previous studies for the liquid Ge0.5Se0.5 system for Ge-Ge Sn(q) showed a peak at around 1.7Å -1 , but the curve is more flat with respect to the others and also respect to ab initio simulations, whose results depend on the choice of the exchange-correlation functional 23,24,45,50 .…”

“…These values are close to those obtained by both experiment and computer simulation studies on liquid GeSe. 23,24,50 Previous studies on the liquid Ge 0.5 Se 0.5 system for Ge−Ge S n (q) showed a peak at around 1.7 Å −1 , but the curve is more flat with respect to the others and also to ab initio simulations, whose results depend on the choice of the exchangecorrelation functional. 23,24,45,50 The Ge−Ge interactions in the liquid reported in Figure 4a show a marked peak at 1.7 Å −1 with a trend similar to those previously obtained, confirming the good accuracy of the force field employed.…”