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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Using Kohn-Sham Orbitals in Symmetry-Adapted Perturbation Theory to Investigate Intermolecular Interactions
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Using Kohn-Sham Orbitals in Symmetry-Adapted Perturbation Theory to Investigate Intermolecular Interactions

机译：在对称自适应微扰理论中使用Kohn-Sham轨道研究分子间的相互作用

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摘要

This is the rust reported use of a hybrid method involving density functional theory (DFf) and symmetryadapted perturbation theory (SAPT) to calculate intermolecular interactions. This work was stimulated by the reported failures of supermolecular DFf calculations to adequately predict intermolecular (and interatomic) interactions, particularly of the van der Waals type. The goals are to develop a hybrid scheme that will calculate intermolecular interaction energies accurately and in a computationally efficient fashion, while including the benefits of the energy decomposition provided by SAPT. The computational savings result from replacing the costly perturbation theory treatment with DFf , which should include the intramolecular correlation effects on the intermolecular interaction energies. The accuracy of this new hybrid approach (labeled SAPT(DFf? is evaluated by comparisons with higher level calculations. The test cases include tIe2, Ar2, Ar- H2, (H2O)2, (HF)2, CO2-CHJCN, and C~-dimethylnitrarnine. The new approach shows mixed results concerning the accuracy of interaction energies. SAPT(DFf) correctly predicts all the qualitative trends in binding energies for all test, cases. This is particularly encouraging in dimmer systems dominated by dispersive interactions where supermolecular DFf fails to predict binding. In addition, the method achieves a drastic reduction {a factor of at least 100) in computational time over the higher level calculations often used to predict these forces. With respect.to quantitative accuracy, this initial hybrid scheme, using the very popular exchange- correlation functional B3L YP, overestimates the second-order energy components (e.g., induction and dispersion ~ terms) for all of the test cases, and subsequently overestimates the total interaction energy for all dimer ~ systems except those heavily dominated by the electrotstatic interactions. The SAPT energy decomposition I points to the use of DFf virtual orbital eigenvalues in the second-order perturbation terms as the likely cause ! for th.is error: These results are consistent ~ith earlier work sug~esting that I?Ff canonical vi~ual orbital I energies obtaln~d from .commonly used functlonals are less than optimal for use In such a perturbatlve scheme. l~ The first-order Interaction energy terms from the SAPT(DFf) are found to be generally more accurate than the second-order terms, and agree well with the benchmark values for dimmers containing molecules with a permanent electric dipole moment. These first-order terms depend only upon the occupied MO eigenvectors, ;: and hence are not affected by the inaccuracies in the Kohn-Sham DFf virtual orbital eigenvalues. These ~ observations encourage future studies utilizing newly reported functionals, some of which have been developed ~ to directly address problems with DFf virtual orbital energies and the asymptotic region of the electron ~ density .
机译：据报道，这是锈病使用混合方法的一种方法，该方法涉及密度泛函理论（DFf）和对称适应扰动理论（SAPT）来计算分子间的相互作用。报道的超分子DFf计算未能充分预测分子间（和原子间）相互作用，特别是范德华类型的相互作用，激发了这项工作。目标是开发一种混合方案，该方案将以计算有效的方式准确地计算分子间相互作用的能量，同时包括SAPT提供的能量分解的好处。计算上的节省是通过用DFf代替了昂贵的扰动理论处理而得出的，该函数应包括分子间相互作用能的分子内相关效应。这种新的混合方法的准确性（通过与更高级别的计算进行比较来评估标记为SAPT（DFf？）。测试案例包括tIe2，Ar2，Ar-H2，（H2O）2，（HF）2，CO2-CHJCN和C 〜-二甲基亚硝胺。新方法显示了关于相互作用能准确性的混合结果。SAPT（DFf）正确预测了所有情况下结合能的所有定性趋势。这在以分散相互作用为主的调光系统中特别令人鼓舞，其中超分子DFf此外，与通常用于预测这些力的高级计算相比，该方法在计算时间上实现了大幅度的减少（至少100倍）。非常流行的交换相关函数B3L YP，高估了所有测试用例的二阶能量分量（例如，归纳和离散项），随后高估了总的所有二聚体系统的相互作用能，除了那些由静电相互作用占主导的系统。 SAPT能量分解I指出在二阶扰动项中使用DFf虚拟轨道特征值是可能的原因！对于这个错误：这些结果与以前的工作是一致的，这表明，在常用的扰动方案中，由常用函数提供的经典范式I能量不是最优值。从SAPT（DFf）得到的一阶相互作用能项通常比二阶项更准确，并且与包含具有永久电偶极矩的分子的二聚体的基准值非常吻合。这些一阶项仅取决于所占据的MO特征向量;并且因此不受Kohn-Sham DFf虚拟轨道特征值的不准确性的影响。这些观察结果鼓励了利用新近报道的功能的未来研究，其中一些功能已经开发出来，可以直接解决DFf虚拟轨道能量和电子密度的渐近区域的问题。

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