第一性原理质心分子动力学模拟高压冰。

First principles centroid molecular dynamics simulation of high pressure ices.

机构信息

Synchrotron Radiation Research Center, Quantum Beam Science Research Directorate (QuBS), National Institutes for Quantum and Radiological Science and Technology (QST), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.

出版信息

J Chem Phys. 2018 Mar 14;148(10):102332. doi: 10.1063/1.5003055.

DOI:10.1063/1.5003055

PMID:29544301

Abstract

The nuclear quantum effects (NQEs) on the structural, elastic, electronic, and vibrational properties of high pressure ices (HPIs) VIII, VII, and X at 270 K were investigated via first principles centroid molecular dynamics (CMD). Our simulations clearly show that even at relatively high temperature of 270 K, the NQEs play a definite role in the pressure-induced proton order (ice VIII)-disorder (ice VII) transition occurring at ∼30 GPa in our HO ice and the subsequent transition to the symmetric phase ice X suggested to occur at ∼80 GPa. The internal pressure computed at constant NVT conditions shows that the NQEs manifest themselves in the equation of state of HPIs. Our employed approach based on first principles CMD for computing vibrational spectra is proved to be able to reproduce well the overall features of the measured infrared and Raman spectra.

摘要

通过中心分子动力学（CMD）的第一性原理计算，研究了核量子效应对 270K 高压冰（HPIs）VIII、VII 和 X 的结构、弹性、电子和振动性质的影响。我们的模拟结果清楚地表明，即使在相对较高的 270K 温度下，核量子效应在压力诱导的质子有序（冰 VIII）-无序（冰 VII）转变中也发挥了一定的作用，该转变发生在我们的 HO 冰中约 30GPa，随后转变为在约 80GPa 下发生的对称相冰 X。在恒 NVT 条件下计算的内压表明，核量子效应在高压冰的状态方程中表现出来。我们采用的基于第一性原理 CMD 计算振动光谱的方法被证明能够很好地再现测量得到的红外和拉曼光谱的整体特征。