Overcoming Artificial Multipoles in Intramolecular Symmetry-Adapted Perturbation Theory
Overcoming Artificial Multipoles in Intramolecular Symmetry-Adapted Perturbation Theory
复制标题
克服分子内对称性微扰理论中的人工多极子
DOI：
10.1021/acs.jpca.2c06465
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Patkowski, Konrad
中科院分区：
文献类型：
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作者：
Luu, Du;Patkowski, Konrad
分子内自适应微扰理论（ISAPT）是一种计算和分解通过连接子C共价连接的两个分子片段A和B之间的非共价相互作用能的方法。然而，现有的ISAPT算法显示了许多碎裂模式（即，特定的分配原子的theA/B/C子系统），包括人为排斥静电能（即使当碎片是氢键）和非常大的和相互抵消的感应和交换感应项的几个问题。我们将这些问题归因于碎片间边界存在人工偶极矩，因为A和B的原子直接连接到它们的混合轨道之一上的缺失电子。因此，我们提出了几种新的分配算法，在一个单占据的链接杂化轨道上，重新分配一个电子，从C到A/B的每一个。一旦这些链接轨道的贡献被添加到碎片密度矩阵，ISAPT静电能，感应能和色散能的计算完全正常进行，交换能的表达式只需要很小的修改。在介绍的链接分割算法中，所谓的ISAPT（SIAO 1）方法（其中链接轨道是通过投影到给定片段的固有原子轨道（IAO）上，然后与该片段的占用空间正交化来获得）导致所有碎片模式的所有ISAPT校正的合理值，并表现出快速和系统的基组收敛。这种改进是通过在碎片间边界处的非物理偶极矩的幅度显著减小（即使不是完全消除）而实现的。我们证明了实用程序的改进ISAPT分区通过检查分子内的相互作用在几个戊二醇异构体，直链和支链烷烃的例子，和一个家庭的N-芳基酰亚胺分子扭转平衡的开放和封闭的构象。
Intramolecular symmetry-adapted perturbation theory (ISAPT) is a method to compute and decompose the noncovalent interaction energy between two molecular fragmentsAandBcovalently connected via a linkerC. However, the existing ISAPT algorithm displays several issues for many fragmentation patterns (that is, specific assignments of atoms to theA/B/Csubsystems), including an artificially repulsive electrostatic energy (even when the fragments are hydrogen-bonded) and very large and mutually cancelling induction and exchange-induction terms. We attribute those issues to the presence of artificial dipole moments at the interfragment boundary, as the atoms ofAandBdirectly connected toCare missing electrons on one of their hybrid orbitals. Therefore, we propose several new partitioning algorithms which reassign one electron, on a singly occupied link hybrid orbital, fromCto each ofA/B. Once the contributions from these link orbitals are added to fragment density matrices, the computation of ISAPT electrostatic, induction, and dispersion energies proceeds exactly as normal, and the exchange energy expressions need only minor modifications. Among the link partitioning algorithms introduced, the so-called ISAPT(SIAO1) approach (in which the link orbital is obtained by a projection onto the intrinsic atomic orbitals (IAOs) of a given fragment followed by orthogonalization to this fragment’s occupied space) leads to reasonable values of all ISAPT corrections for all fragmentation patterns, and exhibits a fast and systematic basis set convergence. This improvement is made possible by a significant reduction in magnitude (even though not a complete elimination) of the unphysical dipole moments at the interfragment boundaries. We demonstrate the utility of the improved ISAPT partitioning by examining intramolecular interactions in several pentanediol isomers, examples of linear and branched alkanes, and the open and closed conformations of a family of N-arylimide molecular torsion balances.