Scalable ab initio fragmentation methods based on a truncated expansion of the non-orthogonal molecular orbital model
Gordon, Mark S.
Iowa State University Digital Repository, Ames IA (United States)
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An alternative formulation of the non-orthogonal molecular orbital model of electronic structure theory is developed based on the expansion of the inverse molecular orbital overlap matrix. From this model, a hierarchy of ab initio fragment-based quantum chemistry methods, referred to as the nth-order expanded non-orthogonal molecular orbital methods, are developed using a minimal number of approximations, each of which is frequently employed in intermolecular interaction theory. These novel methods are compared to existing fragment-based quantum chemistry methods, and the implications of those significant differences, where they exist, between the methods developed herein and those already existing methods are examined in detail. Computational complexities and theoretical scaling are also analyzed and discussed. Future extensions for the hierarchy of methods, to account for additional intrafragment and interfragment interactions, are outlined.
This article is published as Westheimer, Bryce M., and Mark S. Gordon. "Scalable ab initio fragmentation methods based on a truncated expansion of the non-orthogonal molecular orbital model." The Journal of Chemical Physics 155, no. 15 (2021): 154101. DOI: 10.1063/5.0064864 Copyright 2021 The Author(s). Posted with permission. DOE Contract Number(s): AC02-07CH11338