利用一种新发展的从头算演化方法，对高压下固态硅烷进行分子晶体结构预测，重点关注硅烷在25～300 GPa压力区间相结构的变化，以及金属相结构的转变条件。当加压至55 GPa时，除了搜索到与最新金刚石压砧实验结果一致的结构（I‐42d ，I41／a）以外，同时还搜索到新的C2／c结构，并与I41／a结构共同稳定存在于55～240 GPa的压力区间。在上述整个压力范围，硅烷均保持良好的绝缘性，直至压力达到240 GPa才转变为Pbcn结构，并表现出金属性。结果较好地解释了已有的实验高压状态方程数据；验证了硅烷的金属化相变仅发生在200 G Pa以上，排除硅烷在60 GPa发生金属化相变而导致其失去透明性的可能性。
On First Principles of Silane at High Pressure
High‐pressure phases of silane are predicted by using the ab initio evolution theory in pressure region from 25 to 300 GPa .The molecular crystal structure prediction method has been used to search the stable structures of silane .At 55 GPa ,three stable phases have been found ,two of them are in I‐42d and I41/a structures and in a good agreement with the experimental results of diamond anvil cell (DAC) .A new phase has been predicted ,which has C2/c structure .Increasing with pressure ,the I‐42d phase be‐comes unstable ,only C2/c phase is coexistence with I41/a between 55 and 240 GPa ,and both of them keep in insulated state .At pressure increased to 240 GPa ,crystal silane transforms to Pbcn structure and be‐comes a metal .This work well explains the experimental equation of state at high pressure ,and eliminates the possibility that loss of transparency for silane at 60 GPa is due to the metallization .
NETL
NSTL
万方数据
维普
