原子尺寸差效应对Au的势能曲面及玻璃形成能力的影响

Effect of atomic size mismatch on potential energy landscape and glass forming ability for Au

运用分子动力学模拟方法,采用镶嵌原子势,研究了金属Au和AuAu′(Au为正常尺寸的金原子,Au′为半径尺寸变大10%的金原子,两者的原子比例为3:1)在发生玻璃转变过程中的势能曲面,探讨了原子尺寸差效应对势能曲面的影响.我们发现增加原子尺寸差会导致Au的势能曲面发生显著的变化:它使高-低温的内在势能差变大;导致每个温度下内在能量分布变宽,势能曲面变得粗糙;使得体系的海森矩阵特征值分布曲线的峰值变矮,势能曲面上的结构重排方向更少,重排几率更小;导致过冷液态区的流变激活能随温度降低增加更快.以上原子尺寸差效应导致的势能曲面的所有的变化,都有利于提高非晶的形成能力.

Potential energy surface（PES） of pure Au and AuAu’（Au’ represents atoms which radius is 10% larger than normal size Au,the number ratio of Au：Au’= 3：1） during glass transition have been studied by a series of molecular dynamics（MD） simulations with embedded atom method（EAM） potentials.We investigate the effect of atomic size mismatch on PES noting that the PES of Au changes obviously while atomic size mismatch increases.Firstly,we find the inherent structure energy difference between high and low temperature become larger.Secondly,the distribution of inherent energy becomes broaden and the PES becomes crude at each temperature.Thirdly,the number of negative Hessian eigenvalue reduced implying weak atom re-arrangement ability.At last,the activation energy increases more quickly with the decreased temperatures at supercooled liquid region.All changes of PES by atomic size mismatch make for the better glass forming ability.