1ST-PRINCIPLES STATISTICAL-MECHANICS OF STRUCTURAL STABILITY OF INTERMETALLIC COMPOUNDS
1ST-PRINCIPLES STATISTICAL-MECHANICS OF STRUCTURAL STABILITY OF INTERMETALLIC COMPOUNDS
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DOI：
10.1103/physrevb.44.512
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发表时间：
1991-07-01
影响因子：
3.7
通讯作者：
FERREIRA, LG
中科院分区：
文献类型：
--
作者：
LU, ZW;WEI, SH;FERREIRA, LG
虽然作为元素固体，Al、Ni、Cu、Rh、Pd、Pt 和 Au 以面心立方 (fcc) 结构结晶，但在低温下，它们的 50%-50% 化合物表现出一系列结构对称性：CuAu 具有基于 fcc 的 L 1(0) 结构，CuPt 具有菱面体 L1(1) 结构，CuPd 和 AlNi 具有体心立方 B2结构，而 CuRh 不存在（它相分离为 Cu 和 Rh）。现象学方法试图根据原子尺寸、电负性和电子/原子比等经典结构来合理化这种类型的结构选择性。最近，人们尝试根据（量子力学）电子结构来解释这种类型的选择性，例如通过对比各种有序结构的自洽计算的总电子+离子能量。然而，此类计算通常仅从具有 N 个位点的固定晶格上两种类型原子的 2N 种可能配置中选择“直观结构”的一小部分 O10 子集，以寻找最低能量。我们使用 O10 结构总能量的第一性原理计算来定义多自旋伊辛哈密顿量，其基态结构可以使用晶格理论的方法进行系统搜索。扩展我们之前在半导体合金方面的工作 [S.-H. Wei，L. G. Ferreira 和 A. Zunger，物理学家。 Rev. B 41, 8240 (1990)]，此处针对金属间化合物 AlNi、CuRh、CuPd、CuPt 和 CuAu 进行了说明，通过结合使用密度泛函形式（以提取伊辛型相互作用能）和简单的构型搜索策略（以查找基态），从大约 65 000 种构型中识别出了正确的基态。这在电子结构和相位稳定性之间建立了直接和系统的联系。
While as elemental solids, Al, Ni, Cu, Rh, Pd, Pt, and Au crystallize in the face-centered-cubic (fcc) structure, at low temperatures, their 50%-50% compounds exhibit a range of structural symmetries: CuAu has the fcc-based L 1(0) structure, CuPt has the rhombohedral L1(1) structure, and CuPd and AlNi have the body-centered-cubic B2 structure, while CuRh does not exist (it phase separates into Cu and Rh). Phenomenological approaches attempt to rationalize this type of structural selectivity in terms of classical constructs such as atomic sizes, electronegativities, and electron/atom ratios. More recently, attempts have been made at explaining this type of selectivity in terms of the (quantum-mechanical) electronic structure, e.g., by contrasting the self-consistently calculated total electron + ion energy of various ordered structures. Such calculations, however, normally select but a small, O10 subset of "intuitive structures" out of the 2N possible configurations of two types of atoms on a fixed lattice with N sites, searching for the lowest energy. We use instead first-principles calculations of the total energies of O10 structures to define a multispin Ising Hamiltonian, whose ground-state structures can be systematically searched by using methods of lattice theories. Extending our previous work on semiconductor alloys [S.-H. Wei, L. G. Ferreira, and A. Zunger, Phys. Rev. B 41, 8240 (1990)], this is illustrated here for the intermetallic compounds AlNi, CuRh, CuPd, CuPt, and CuAu, for which the correct ground states are identified out of approximately 65 000 configurations, through the combined use of the density-functional formalism (to extract Ising-type interaction energies) with a simple configurational-search strategy (to find ground states). This establishes a direct and systematic link between the electronic structure and phase stability.