论文标题
通过基于对称的分类来确定合金的基态
Determining ground states of alloy by a symmetry-based classification
论文作者
论文摘要
减少候选结构的数量对于提高全球优化的效率至关重要。本文中，我们证明了基于对称性的原子分类模型（ACM）可以描述广义的哈密顿量，从而为第一原理计算生成了有效的候选者，以直接确定合金的基态。可以通过逐步求解凸船体来提前获得候选人，因为ACM的相关函数可以根据定义的索引$ L $将其分为各种子空间。作为一个重要的推论，该指数可以转换为Wyckoff位置的数量，从而揭示了几何对称性对结构稳定性的主要影响。以Ni-PT，AG-PD，OS-RU，IR-RU和MO-RU为示例，我们不仅在以前的理论和实验结果中确定稳定的结构，而且还可以预测数十个具有较低地层能量的配置，例如Ag $ _ {0.5} $ _ {0.5} $ PD $ _ {0.5} $ {0.5} $（$ fd $ - $ 3M $ - 3M $ - 3MM） Os$_{0.5}$Ru$_{0.5}$ ($Pnma$), Ir$_{1/3}$Ru$_{2/3}$ ($P6_{3}/mmc$), and Mo$_{0.25}$Ru$_{0.75}$ ($Cmcm$).
Reducing the number of candidate structures is crucial to improve the efficiency of global optimization. Herein, we demonstrate that the generalized Hamiltonian can be described by the atom classification model (ACM) based on symmetry, generating competent candidates for the first-principles calculations to determine ground states of alloy directly. The candidates can be obtained in advance through solving the convex hull step by step, because the correlation functions of ACM can be divided into various subspace according to the defined index $l$. As an important inference, this index can be converted to the number of Wyckoff positions, revealing the dominant effect of geometry symmetry on structural stability. Taking Ni-Pt, Ag-Pd, Os-Ru, Ir-Ru and Mo-Ru as examples, we not only identify the stable structures in previous theoretical and experimental results, but also predict a dozen of configurations with lower formation energies, such as Ag$_{0.5}$Pd$_{0.5}$ ($Fd$-$3m$), Os$_{0.5}$Ru$_{0.5}$ ($Pnma$), Ir$_{1/3}$Ru$_{2/3}$ ($P6_{3}/mmc$), and Mo$_{0.25}$Ru$_{0.75}$ ($Cmcm$).
