硝酸铷高压相变和物理性质的第一性原理研究  

First-Principles Study of the High-Pressure Phase Transition and Physical Properties of Rubidium Nitrate

作　　者：王晓雪 丁雨晴 王晖 WANG Xiaoxue;DING Yuqing;WANG Hui(School of Physics and Electronic Engineering,Harbin Normal University,Harbin 150025,Heilongjiang,China)

机构地区：[1]哈尔滨师范大学物理与电子工程学院,黑龙江哈尔滨150025

出　　处：《高压物理学报》2024年第4期24-33,共10页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金(11974135)。

摘　　要：采用基于密度泛函理论的第一性原理计算,并结合CALYPSO晶体结构预测软件,系统地探索了零温下RbNO_(3)的高压结构与物理性质。基于RbNO_(3)-Ⅳ相的实验数据,比较了4种不同泛函的准确性,发现PBEsol泛函的准确性最高。基于该泛函预测到RbNO_(3)在零温下的相变序列为R3m→Pnma→Pmmn(实验Ⅴ相),相变压强依次为1.7和8.2 GPa,2次相变均为一级相变,体积坍塌率分别为3.73%和2.54%。研究结果表明,低压下RbNO_(3)可能存在有别于实验(常温常压下)给出的P31结构的低温新相。3个相在各自能量稳定的压强范围内均满足“伯恩-黄昆”弹性稳定性判据,且在整个布里渊区中均不存在声子虚频现象,表明它们均具有动力学稳定性。电子性质分析表明,3个相均为半导体,相变引起的带隙变化普遍较小,加压普遍地抑制了铷离子的电荷向硝酸根离子转移。所预测的高压相变序列及各个相的弹性、晶格动力学、电子结构性质可为后续实验与理论研究提供参考。The high-pressure structure and physical properties of RbNO_(3) at zero temperature was systematically explored using first-principles calculations based on density generalized theory combined with CALYPSO crystal structure predictions.The accuracy of four different functionals was compared based on experimental data of the RbNO_(3)-Ⅳ phase,and the revised PBE for solids(PBEsol)functional was found to be the most reliable.The zero-temperature phase transition sequence of RbNO_(3) predicted is R3m→Pnma→Pmmn(experimental phase Ⅴ)based on the PBEsol functional,and the two phase transition pressures are 1.7 and 8.2 GPa.The two phase transitions are first-order phase transitions,and the volume collapse rates reach 3.73% and 2.54%,respectively.This suggests that RbNO_(3) at low pressure may have new low-temperature phases those are different from P31 structure given by experiment in the room temperature and ambient pressure.In the energy-stabilized pressure interval,all three phases satisfy the“Born-Huangkun”elastic stability criteria,and there is no phonon virtual frequency phenomenon in the whole Brillouin zone,which indicates that they are dynamically stable structures.The electronic property analysis showed that the three phases are semiconductors,and the band gap changes caused by the phase transition are generally small,but the pressure generally inhibits the charge transfer from alkali metal ions to nitrate ions.The high-pressure phase transition sequence predicted in this paper and the elasticity,lattice dynamics,and electronic structure properties of the individual phases can provide a reference for subsequent experimental and theoretical studies.

关 键 词：高压 相变 第一性原理 RbNO_(3) 

分 类 号：O521.2[理学—高压高温物理] O469[理学—物理]