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arXiv 1706.07982physics.chem-ph
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DFT中三体相互作用的性质:交换效应和极化效应

The nature of three-body interactions in DFT: exchange and polarization effects

Michał Hapka, Łukasz Rajchel, Marcin Modrzejewski, Rainer Schäffer, Grzegorz Chałasiński, Małgorzata M. Szczęśniak

摘要:

我们提出了一个物理动机的DFT 3-体非加性相互作用能分解成交换和密度变形(极化)组件。交换分量代表了三聚体的波函数中的泡利排斥效应,并且被发现对于密度泛函近似(DFAs)是具有挑战性的。剩余的密度变形非加性较少依赖于DFA。对稀有气体原子三聚体、Ar $_2$ -HX(X = F,Cl)配合物、氢键和范德华小分子体系进行了数值模拟。没有一个测试的半局部,混合,和范围分离的DFA适当占非加性交换分散键合三聚体。相比之下,氢键系统的范围分离的混合动力车实现了定性协议内的20%的参考交换能量。只有当单体通过Hartree-Fock势在无色散的Pauli Blockade方案中相互作用时,才能获得所有系统的可靠性能。此外,我们确定了非加性的二阶交换色散能量作为一个重要的,但被忽视的贡献力场般的色散校正。我们的研究结果表明,范围分离的泛函不包括这个组件,虽然半局部和全球混合DFAs出现模仿它在短期内。

英文摘要:

We propose a physically motivated decomposition of DFT 3-body nonadditive interaction energies into the exchange and density-deformation (polarization) components. The exchange component represents the effect of the Pauli exclusion in the wave function of the trimer and is found to be challenging for density functional approximations (DFAs). The remaining density-deformation nonadditivity is less dependent upon the DFAs. Numerical demonstration is carried out for rare gas atom trimers, Ar$_2$-HX (X = F, Cl) complexes, and small hydrogen-bonded and van der Waals molecular systems. None of the tested semilocal, hybrid, and range-separated DFAs properly accounts for the nonadditive exchange in dispersion-bonded trimers. By contrast, for hydrogen-bonded systems range-separated hybrids achieve a qualitative agreement to within 20% of the reference exchange energy. A reliable performance for all systems is obtained only when the monomers interact through the Hartree-Fock potential in the dispersion-free Pauli Blockade scheme. Additionally, we identify the nonadditive second-order exchange-dispersion energy as an important but overlooked contribution in force-field-like dispersion corrections. Our results suggest that range-separated functionals do not include this component although semilocal and global hybrid DFAs appear to imitate it in the short range.

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