Embedded, graph‐theoretically defined many‐body approximations for wavefunction‐in‐DFT and DFT‐in‐DFT : Applications to gas‐ and condensed‐phase ab initio molecular dynamics, and potential surfaces for quantum nuclear effects
Embedded, graph‐theoretically defined many‐body approximations for wavefunction‐in‐DFT and DFT‐in‐DFT : Applications to gas‐ and condensed‐phase ab initio molecular dynamics, and potential surfaces for quantum nuclear effects
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DOI：
10.1002/qua.26244
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发表时间：
2020-05
影响因子：
2.2
通讯作者：
Timothy C. Ricard;Anup Kumar;S. Iyengar
中科院分区：
文献类型：
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作者：
Timothy C. Ricard;Anup Kumar;S. Iyengar
我们提出了一种图论方法，以一种有效的方式自适应地计算多体近似，以执行(A)以密度泛函(DFT)为代价的中大型分子团簇的精确后Hartree-Fock(HF)从头算分子动力学(AIMD)，(B)以纯密度泛函为代价的用于凝聚相模拟的混合DFT电子结构计算，(C)用于气相AIMD和凝聚相研究的低成本的动态基外推，以及(D)以DFT为代价的精确的后HF能级势能面的量子核效应。我们方法的显著特征是类似于ONIOM的，因为(A)整个系统(团簇或凝聚相)的计算是在较低的理论水平上进行的(凝聚相的纯DFT或分子体系的混合DFT)，以及(B)通过图论方法结合的修正项来改进这种近似，该修正项捕捉了较高理论水平(凝聚相的混合DFT；团簇的CCSD或MP2)内直到任何给定阶数的所有多体相互作用。具体地说，将感兴趣的化学区域粗粒度化为一组节点，然后根据给定的局部包络(或阈值)相互作用的定义将这些节点连接起来形成边。节点和边一起定义了一个图形，该图形形成了开发多体展开的基础。这些方法是通过(A)质子化水团簇和多肽碎片的从头算动力学研究，(B)离子通道等一维水链的势能面计算，以及(C)利用二维周期边界条件对含有有机吸附物的均相和非均相表面的构象稳定性和晶格能研究的结果。
We present a graph-theoretic approach to adaptively compute many-body approximations in an efficient manner to perform (a) accurate post-Hartree – Fock (HF) ab initio molecular dynamics (AIMD) at density functional theory (DFT) cost for medium-to large-sized molecular clusters, (b) hybrid DFT electronic structure calculations for condensed-phase simulations at the cost of pure density functionals, (c) reduced-cost on-the-fly basis extrapolation for gas-phase AIMD and condensed phase studies, and (d) accurate post-HF-level potential energy surfaces at DFT cost for quantum nuclear effects. The salient features of our approach are ONIOM-like in that (a) the full system (cluster or condensed phase) calculation is performed at a lower level of theory (pure DFT for condensed phase or hybrid DFT for molecular systems), and (b) this approximation is improved through a correction term that captures all many-body interactions up to any given order within a higher level of theory (hybrid DFT for condensed phase; CCSD or MP2 for cluster), combined through graph-theoretic methods. Specifically, a region of chemical interest is coarse-grained into a set of nodes and these nodes are then connected to form edges based on a given definition of local envelope (or threshold) of interactions. The nodes and edges together define a graph, which forms the basis for developing the many-body expansion. The methods are demonstrated through (a) ab initio dynamics studies on protonated water clusters and polypeptide fragments, (b) potential energy surface calculations on one-dimensional water chains such as those found in ion channels, and (c) conformational stabilization and lattice energy studies on homogeneous and heterogeneous surfaces of water with organic adsorbates using two-dimensional periodic boundary conditions.