晶体材料的近视性与晶间脆性
Nearsightedness of Crystalline Materials and Intergranular Embrittlement
摘要：
我们对材料设计的追求通常设想作为第一步，将材料概念分解为有意义的原子尺度邻域。整体材料的性能，然后被认为是从这些简单得多的区域的综合性能。正是电子物质（NEM）原理的短视为这种“分而治之”的方法提供了严格的理由。NEM断言，材料属性可能会受到扰动的显著影响，无论扰动有多大，仅在大小为$R$的邻域内。虽然NEM假设存在有意义的原子尺度邻域，但这些区域大多是凭经验确定的。在本文中，我们提出了一种方法来划分真正的材料到有意义的邻居所确定的拓扑结构的电荷密度。我们推广这种方法，通过应用相同的元素结晶材料，然后使用这些社区来模拟铋原子分离到铜晶界的脆化效应，以确定代表的街区。我们表明，脆化是杂质原子引起的铜近视增强的结果。我们进一步认为，正如近视在介导脆化中起着被忽视的作用一样，它也可能是一个重要的因素，影响了广泛的未解决的问题，如能量聚焦现象和酶动力学。
英文摘要：
Our quest to design materials often envisions as a first step the conceptual decomposition of a material into meaningful atomic scale neighborhoods. The performance of the monolithic material is then seen to arise from the combined properties of these much simpler regions. It is the nearsightedness of electronic matter (NEM) principle that provides the rigorous justification for this "divide and conquer" approach. NEM asserts that a material property may be significantly affected by a perturbation, no matter how large, only over a neighborhood of size $R$. Though NEM posits the existence of meaningful atomic scale neighborhoods, for the most part these regions are identified empirically. In this paper we propose a methodology to divide real materials into meaningful neighborhoods determined by the topology of the charge density. We generalize this approach by applying the same to determine neighborhoods representative of elemental crystalline materials and then use these neighborhoods to model the embrittling effects of bismuth atoms segregated to copper grain boundaries. We show that embrittlement is the result of impurity atom-induced enhancements of copper nearsightedness. We further suggest that just as nearsightedness plays an overlooked role mediating embrittlement, it may also be an important factor affecting a broad range of unresolved problems as apparently diverse as energy focussing phenomena and enzyme kinetics.
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