First principles thermodynamics calculation with controlled accuracy in multicomponent systems

提出了一种考虑远程相互作用的第一性原理热力学计算方法。首先，我们开发了计算远程相互作用的源代码，并将该程序应用于黄铜矿结构的点电荷模型。然后，我们将该方法应用于MgAl_2O_4尖晶石阳离子位的有序-无序行为。我们发现，要准确地预测具有异价离子构型的多组分体系的有序-无序行为，必须准确地考虑远程相互作用。此外，我们还提出了一种基于结构选择的聚类展开方法精度评价方法。利用该方法，提高了聚类展开法对多种结构的精度。

We proposed a procedure of the first principles thermodynamic calculation with considering long-range interactions. First we developed source codes for calculating the long-range interaction and applied the procedure to a point-charge model of the chalcopyrite structure. Then, we applied the procedure to order-disorder behavior on cation sites in MgAl_2O_4 spinel. We found that it is essential to consider the long-range interactions accurately in order to predict the order-disorder behavior accurately in multicomponent system with configurations of heterovalent ions. In addition, we proposed a procedure for evaluating the accuracy of the cluster expansion method based on the structure selection. Using the procedure, the accuracy of the cluster expansion method for a wide range of structures is improved.