Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA.
J Chem Phys. 2012 Aug 14;137(6):064113. doi: 10.1063/1.4742816.
Fragment-based quantum chemistry methods are a promising route towards massively parallel electronic structure calculations in large systems. Unfortunately, the literature on this topic consists of a bewildering array of different methods, with no clear guiding principles to choose amongst them. Here, we introduce a conceptual framework that unifies many of these ostensibly disparate approaches. The common framework is based upon an approximate supersystem energy formula for a collection of intersecting (i.e., overlapping) fragments. This formula generalizes the traditional many-body expansion to cases where the "bodies" (fragments) share some nuclei in common, and reduces to the traditional many-body expansion for non-overlapping fragments. We illustrate how numerous fragment-based methods fit within this framework. Preliminary applications to molecular and ionic clusters suggest that two-body methods in which dimers are constructed from intersecting fragments may be a route to achieve very high accuracy in fragment-based calculations.
基于片段的量子化学方法是在大型系统中进行大规模并行电子结构计算的一种很有前途的途径。不幸的是，这个主题的文献中包含了各种各样令人困惑的不同方法，没有明确的指导原则来选择它们。在这里，我们引入了一个统一了许多这些表面上不同方法的概念框架。该通用框架基于相交（即重叠）片段集合的近似超体系能量公式。该公式将传统的多体展开推广到“体”（片段）共享一些共同核的情况，并简化为非重叠片段的传统多体展开。我们说明了许多基于片段的方法如何适应该框架。初步应用于分子和离子簇表明，通过相交片段构建二聚体的二体方法可能是实现基于片段计算中非常高精度的一种途径。
