Molecular dynamics simulations of a femtosecond-laser-induced solid-to-solid transition in antimony
Molecular dynamics simulations of a femtosecond-laser-induced solid-to-solid transition in antimony
复制标题
DOI：
10.1007/s00339-017-1216-7
复制
发表时间：
2017-09-01
影响因子：
2.7
通讯作者：
Garcia, Martin E.
中科院分区：
文献类型：
--
作者：
Bauerhenne, Bernd;Zijlstra, Eeuwe S.;Garcia, Martin E.
我们用从头算分子动力学（MD）模拟了激光激发锑在由864个原子组成的超级单体上的超快动力学。对于低激光影响（在我们的理论中由中等电子温度表示），我们得到了众所周知的晶体平面在[111]方向上的振荡，对应于振幅较大的相干A（1g）声子。对于低于熔化阈值的大影响（高电子温度），模拟表明可能从最初的佩尔斯扭曲的A7结构转变为没有佩尔斯扭曲的结构。然而，有限尺寸效应引起的波动阻碍了这种非热相变的清晰演示。因此，基于从头算的结果，我们推导出了一个依赖于电子温度的分析势，并用它在含有多达10(6)个原子的超级电池中进行大规模的原子动力学模拟。该势可以清晰地再现从头算结果中观察到的A（1g）相干声子的非热现象和激发。最重要的是，由于有限尺寸效应的最小化，我们的大规模模拟预测了从佩尔斯扭曲的A7结构到没有佩尔斯扭曲的结构的干净的非热转变。
We performed ab initio molecular dynamics (MD) simulations to describe the ultrafast dynamics of laser-excited antimony on a supercell consisting of 864 atoms. For low laser fluences (represented in our theory by moderate electronic temperatures), we obtain the well-known oscillations of the crystal planes in the [111] direction, corresponding to the large amplitude coherent A(1g) phonon. For large fluences (high electronic temperature) below the melting threshold, simulations suggest a possible transition from the initial, Peierls-distorted A7 structure into a structure without Peierls distortion. However, fluctuations due to finite size effects prevent a clean demonstration of such a nonthermal phase transition. Therefore, and based on the ab initio results, we derived an analytical potential depending on the electronic temperature and used it to perform large-scale MD simulations in supercells containing up to 10(6) atoms. The potential can clearly reproduce the nonthermal phenomena and the excitation of the A(1g) coherent phonon observed in the ab initio results. Most importantly, due to the minimization of finite size effects, our large-scale simulations predict a clean nonthermal transition from the Peierls-distorted A7 structure into a structure without Peierls distortion.