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Dynamic stabilization of cubic CaSiO_3 perovskite at high temperatures and pressures from ab initio molecular dynamics

机译:从头算分子动力学来看,高温和高压下立方CaSiO_3钙钛矿的动态稳定

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摘要

The stability of cubic CaSiO_3 perovskite (CaPv) at high temperatures and pressures is investigated by vibrational normal-mode analysis. We compute power spectra of mode autocorrelation functions using a recently developed hybrid approach combining ab initio molecular dynamics with lattice dynamics. These power spectra, together with the probability distributions of atomic displacements, indicate that cubic CaPv is stabilized at T ~ 600 K and P ~ 26 GPa. We then utilize the concept of phonon quasiparticles to characterize the vibrational properties of cubic CaPv at high temperature and obtain anharmonic phonon dispersions through the whole Brillouin zone. Such temperature-dependent phonon dispersions pave the way for more accurate calculations of free-energy, thermodynamic, and thermoelastic properties of cubic CaPv at Earth's lower mantle conditions.
机译:通过振动常模分析研究了立方晶CaSiO_3钙钛矿(CaPv)在高温和高压下的稳定性。我们使用结合了从头算分子动力学和晶格动力学的最新开发的混合方法,计算模式自相关函数的功率谱。这些功率谱以及原子位移的概率分布表明,立方CaPv稳定在T〜600 K和P〜26 GPa。然后,我们利用声子准粒子的概念来表征立方CaPv在高温下的振动特性,并获得整个布里渊区的非谐声子色散。这种与温度有关的声子分散体为在地球下地幔条件下更精确地计算立方CaPv的自由能,热力学和热弹性特性铺平了道路。

著录项

  • 来源
    《Physical review》 |2014年第9期|094109.1-094109.9|共9页
  • 作者单位

    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA,Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing 100049, China;

    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA;

    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA,Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA;

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  • 正文语种 eng
  • 中图分类
  • 关键词

    phase changes;

    机译:相变;

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