极端条件下非谐性对声波速度的影响
Impact of anharmonicity on sound wave velocities at extreme conditions
摘要：
极端条件下材料声波传播速度的理论计算对各个领域，特别是电子物理学都有重要意义。例如，声波通过富含铁的固体地球内核传播的地震数据一直是阐明其性质和建立模型的主要来源。由于在非常高的温度和压力下的实验室实验是不平凡的，从头计算预测是无价的。然而，后者往往不同意实验。我们注意到，许多试图计算物质在极端条件下的声波速度的量子力学为基础的方法的框架内没有考虑到非谐原子振动的影响。我们展示了如何将非谐效应纳入从头计算，并证明，特别是它们可能是不可忽略的铁在地球的核心。因此，我们开辟了一条途径，协调实验和从头算理论。
英文摘要：
Theoretical calculations of sound-wave velocities of materials at extreme conditions are of great importance to various fields, in particular geophysics. For example, the seismic data on sound-wave propagation through the solid iron-rich Earth's inner core have been the main source for elucidating its properties and building models. As the laboratory experiments at very high temperatures and pressures are non-trivial, ab initio predictions are invaluable. The latter, however, tend to disagree with experiment. We notice that many attempts to calculate sound-wave velocities of matter at extreme conditions in the framework of quantum-mechanics based methods have not been taking into account the effect of anharmonic atomic vibrations. We show how anharmonic effects can be incorporated into ab initio calculations and demonstrate that in particular they might be non-negligible for iron in Earth's core. Therefore, we open an avenue to reconcile experiment and ab initio theory.
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