First-principles calculation of structural stability,lattice dynamic and thermodynamic properties of BeX (X = S,Se and Te) compounds under high pressure |
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| Authors: | Zhi-Cheng Guo Fen Luo Guang-Fu Ji Ling-Cang Cai |
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| Institution: | 1. Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;2. National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China;3. Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621900, China;4. National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China |
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| Abstract: | The phase transitions, lattice dynamical and thermodynamic properties of BeS, BsSe and BeTe at high pressure have been investigated with the density functional theory. The calculated equilibrium structural parameters agree well with the available experimental and theoretical values. The phase transition pressures from the zinc-blende (ZB) to the nickel arsenide (NiAs) phase of these compounds are determined. The calculated phonon dispersion curves of these compounds in ZB phase at zero pressure do not show any anomaly or instability. Dynamically, the ZB phase of BeS, BeSe and BeTe is found to be stable near transition pressures PT. Within the quasiharmonic approximation, the thermodynamic properties including the thermal expansion coefficient, heat capacity at constant volume, heat capacity at constant pressure and entropy are predicted. |
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| Keywords: | lattice dynamic thermodynamic properties density functional theory |
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