Phase diagrams, thermodynamic properties and sound velocities derived from a multiple Einstein method using vibrational densities of states: an application to MgO–SiO2
Phase diagrams, thermodynamic properties and sound velocities derived from a multiple Einstein method using vibrational densities of states: an application to MgO–SiO2
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DOI：
10.1007/s00269-016-0835-4
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发表时间：
2016
影响因子：
1.4
通讯作者：
M. Jacobs;R. Schmid-Fetzer;A. P. Berg
中科院分区：
文献类型：
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作者：
M. Jacobs;R. Schmid-Fetzer;A. P. Berg
在以前的论文中，我们展示了一种技术，简化了Kieffer的晶格振动方法，通过表示多个爱因斯坦频率的振动态密度。在这里，我们表明，这种技术可以应用于构建一个热力学数据库，准确地表示热力学性质和系统中的物质的相图MgO-SiO2。我们扩展了我们的技术，以获得在这个系统中的压力-温度空间的相关相的剪切模量。对于数据库的建设，我们使用最近测得的热量和体积数据。我们表明，将振动态密度从头算方法预测到我们的模型，使不同的实验数据集之间的热容量的歧视。我们展示了一种通用的技术来优化在VDOS中的爱因斯坦频率的数量，使得热力学性质的影响微不足道。这种技术允许构建克隆的数据库，我们证明了VDOS有显着的热容量和熵的影响，并对体积属性的影响微不足道。
In a previous paper, we showed a technique that simplifies Kieffer’s lattice vibrational method by representing the vibrational density of states with multiple Einstein frequencies. Here, we show that this technique can be applied to construct a thermodynamic database that accurately represents thermodynamic properties and phase diagrams for substances in the system MgO–SiO2. We extended our technique to derive shear moduli of the relevant phases in this system in pressure–temperature space. For the construction of the database, we used recently measured calorimetric and volumetric data. We show that incorporating vibrational densities of states predicted from ab initio methods into our models enables discrimination between different experimental data sets for heat capacity. We show a general technique to optimize the number of Einstein frequencies in the VDoS, such that thermodynamic properties are affected insignificantly. This technique allows constructing clones of databases from which we demonstrate that the VDoS has a significant effect on heat capacity and entropy, and an insignificant effect on volume properties.