Calculation and interpretation of classical turning surfaces in solids
Calculation and interpretation of classical turning surfaces in solids
复制标题
DOI：
10.1038/s41524-020-00479-0
复制
发表时间：
2021-02
影响因子：
9.7
通讯作者：
Aaron D. Kaplan;S. Clark;K. Burke;J. Perdew
中科院分区：
文献类型：
--
作者：
Aaron D. Kaplan;S. Clark;K. Burke;J. Perdew
经典转向表面的科恩-沙姆潜力的经典允许区域（汽车）从经典禁止区域（CFRs）。它们对于理解分子的许多化学性质是有用的，但不一定存在于固体中，因为固体的密度永远不会衰减到零。在平衡几何，我们发现CFRs是不存在的完美的金属，在共价半导体在平衡状态下罕见，但常见的离子和分子晶体。在所有材料中，CFRs的出现或增长是由于核间距均匀扩大。它们也可以出现在金属中的单空位上。几个近似的密度泛函和代码的计算证实了这些行为。传导的经典图像表明，汽车应该在金属中连接，在宽间隙绝缘体中断开，并且在极端压缩和膨胀的极限中得到证实。令人惊讶的是，许多半导体在平衡状态下没有CFR，这是密度泛函结构的一个关键发现。尽管如此，仍然可以推断出与绝缘行为的强相关性。此外，所有情况下的平衡键长可以从键型和自由原子或离子的经典转弯半径的总和来估计。
Classical turning surfaces of Kohn–Sham potentials separate classically allowed regions (CARs) from classically forbidden regions (CFRs). They are useful for understanding many chemical properties of molecules but need not exist in solids, where the density never decays to zero. At equilibrium geometries, we find that CFRs are absent in perfect metals, rare in covalent semiconductors at equilibrium, but common in ionic and molecular crystals. In all materials, CFRs appear or grow as the internuclear distances are uniformly expanded. They can also appear at a monovacancy in a metal. Calculations with several approximate density functionals and codes confirm these behaviors. A classical picture of conduction suggests that CARs should be connected in metals, and disconnected in wide-gap insulators, and is confirmed in the limits of extreme compression and expansion. Surprisingly, many semiconductors have no CFR at equilibrium, a key finding for density functional construction. Nonetheless, a strong correlation with insulating behavior can still be inferred. Moreover, equilibrium bond lengths for all cases can be estimated from the bond type and the sum of the classical turning radii of the free atoms or ions.