Combining experimental and computational approaches to determine high P and T thermal conductivity of CaGeO3 and MgSiO3 perovskite

了解矿物在地球深部条件下的热输运特性，对于我们理解其热状态和随地质时间的演化是至关重要的。极端压力(P)和温度(T)条件下晶格热导率(K)的实验测量是非常具有挑战性的，而测量它的计算方法可以为我们理解行星的热态做出重要贡献。我们建议使用原子模拟的最新技术，第一原理分子动力学(FPMD)，通过表征k所依赖的非简谐振动性质，计算与下地幔有关的条件下的地幔矿物的k(P，T)。为了测试该方法的第一性原理实现，我们首先考虑氧化镁方镁石的k(P，T)，然后我们将对CaGeO钙钛矿进行计算，并将其与我们将在0-20 Gpa压力下原位测量的k(T)值进行比较。在针对这些数据测试和进一步改进了我们的方法之后，我们将继续计算与整个下地幔相关的条件下的镁硅钙钛矿的k(P，T)。然后，我们将评估这些结果对现有热导率压力依赖模型的影响，以及地球的热演化。

Knowledge of the heat transport properties of minerals at deep Earth conditions is essential for our understanding of its thermal state and evolution over geological time. Experimental measurement of lattice thermal conductivity (k) at extreme pressure (P) and temperature (T) conditions is very challenging, and computational approaches to its determination can make a significant contribution to our understanding of the thermal state of the planet. We propose to use current state of the art in atomistic simulation, first-principles molecular dynamics (FPMD), to compute k(P,T) for mantle minerals at conditions relevant to the lower mantle, by characterizing the anharmonic vibrational properties on which k depends. To test our first principles implementation of the method, we will first consider k(P,T) for MgO periclase, whereafter we will perform calculations for CaGeO3 perovskite, which we will compare to k(T) values that we will measure in situ at pressures 0 – 20 GPa. Having tested and further improved our method against these data, we will proceed to calculate k(P,T) for MgSiO3 perovskite at conditions relevant to the entire lower mantle. We will then evaluate the implications of these results for existing models of the pressure dependence of thermal conductivity, as well as the thermal evolution of Earth.