Ab initio lattice thermal conductivity of MgSiO3 across the perovskite-postperovskite phase transition
Ab initio lattice thermal conductivity of MgSiO3 across the perovskite-postperovskite phase transition
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DOI：
10.1103/physrevb.103.144103
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发表时间：
2021-01
影响因子：
3.7
通讯作者：
Zhen Zhang;R. Wentzcovitch
中科院分区：
文献类型：
--
作者：
Zhen Zhang;R. Wentzcovitch
利用声子准粒子方法，结合\textit{从头}算分子动力学和晶格动力学模拟，研究了下地幔高压-高温条件下MgSiO $_3$后钙钛矿（MgPPv）的晶格热导率（$\kappa_{lat}$）。从声子准粒子计算中提取声子寿命，从非谐波声子色散中计算声子群速度，原则上完全捕获非谐波。结果表明，在整个最下地幔，包括D′区，MgPPv的$\kappa_{lat}$值为25% larger than that of MgSiO$_3$ perovskite (MgPv), mainly due to MgPPv's higher phonon velocities. Such a difference in phonon velocities between the two phases originates in the MgPPv's relatively smaller primitive cell. Systematic results of temperature and pressure dependences of both MgPPv's and MgPv's $\kappa_{lat}$ are demonstrated.
Lattice thermal conductivity ($\kappa_{lat}$) of MgSiO$_3$ postperovskite (MgPPv) under the Earth's lower mantle high pressure-temperature conditions is studied using the phonon quasiparticle approach by combing \textit{ab initio} molecular dynamics and lattice dynamics simulations. Phonon lifetimes are extracted from the phonon quasiparticle calculations, and the phonon group velocities are computed from the anharmonic phonon dispersions, which in principle capture full anharmonicity. It is found that throughout the lowermost mantle, including the D"region, $\kappa_{lat}$ of MgPPv is ~25% larger than that of MgSiO$_3$ perovskite (MgPv), mainly due to MgPPv's higher phonon velocities. Such a difference in phonon velocities between the two phases originates in the MgPPv's relatively smaller primitive cell. Systematic results of temperature and pressure dependences of both MgPPv's and MgPv's $\kappa_{lat}$ are demonstrated.