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High Pressure Structural Instability and Thermal Properties of Rutile TiO2 from First-principles
Cui-e Hu,Zhao-yi Zeng*,Chun-yang Kong,Yu-ting Cui,Lin Zhang,Ling-cang Cai
Author NameAffiliationE-mail
Cui-e Hu College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China;National Key Laboratory for Shock Wave and Detonation hysics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900,  
Zhao-yi Zeng* College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China;National Key Laboratory for Shock Wave and Detonation hysics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, zhaoyizeng@126.com 
Chun-yang Kong College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China  
Yu-ting Cui College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China  
Lin Zhang National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China  
Ling-cang Cai National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China  
Abstract:
We report a first-principles calculation to investigate the structural instability of rutile TiO2. The high pressure structural parameters are well reproduced. The calculated phonon disper-sion curves agree with experiments at zero pressure. Under compression, we capture a large softening around Γ point, which indicates the structural instability. From the high pressure elastic constants, we find that the rutile TiO2 is unstable when the applied pressure is larger than 17.7 GPa. Within the quasi-harmonic approximation, the thermal equation of state, thermal expansion oefficient, bulk modulus, and entropy are well reproduced. The thermal properties confirm the available experimental data and are extended to a wider pressure and temperature range.
Key words:  TiO2, Phonon dispersion, Thermodynamics, Density functional theory
FundProject:
第一性原理计算高压下金红石TiO2的结构不稳定性及热学性质
胡翠娥,曾召益*,孔春阳,崔玉亭,张林,蔡灵仓
摘要:
采用第一性原理计算研究了金红石TiO2结构在高压下的不稳定性及热力学性质. 计算的高压下结构参数和零压的声子色散曲线与实验数据十分吻合. 进一步模拟了在不同压力下的声子曲线,在压力下,声子曲线不断软化,?点附近的振动频率不断减小直至虚频,意味着结构的不稳定,根据计算的不同压力下的弹性常数获得了其力学不稳定性,结果表明金红石结构TiO2在压力高于17.7 GPa时变得不稳定. 根据准谐近似,获得了金红石TiO2结构的热力学性质,计算结果与现有
关键词:  TiO2,声子色散曲线,热力学性质,密度泛函理论
DOI:10.1063/1674-0068/27/01/69-74
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