Ramos Chloe, Janesko Benjamin G
Department of Chemistry and Biochemistry, Texas Christian University, 2800 S. University Dr., Fort Worth, Texas 76129, USA.
J Chem Phys. 2020 Oct 28;153(16):164116. doi: 10.1063/5.0025160.
The rung-3.5 approach to density functional theory constructs nonlocal approximate correlation from the expectation values of nonlocal one-electron operators. This offers an inexpensive solution to hybrid functionals' imbalance between exact nonlocal exchange and local approximate correlation. Our rung-3.5 correlation functionals also include a local complement to the nonlocal ingredient, analogous to the local exchange component of a hybrid functional. Here, we use the density matrix expansion (DME) to build rung-3.5 complements. We demonstrate how these provide a measure of local fractional occupancy and use them to approximate the flat-plane condition. We also use these complements in a three-parameter nonlocal correlation functional compatible with full nonlocal exchange. This functional approaches the accuracy of widely used hybrids for molecular thermochemistry and kinetics. The DME provides a foundation for practical, minimally empirical, nonlocal correlation functionals compatible with full nonlocal local exchange.
密度泛函理论的 rung-3.5 方法通过非局部单电子算符的期望值构建非局部近似相关。这为混合泛函在精确非局部交换与局部近似相关之间的不平衡提供了一种低成本的解决方案。我们的 rung-3.5 相关泛函还包括对非局部成分的局部补充，类似于混合泛函的局部交换成分。在此，我们使用密度矩阵展开（DME）来构建 rung-3.5 补充。我们展示了这些补充如何提供局部分数占据的度量，并使用它们来近似平面条件。我们还在与完全非局部交换兼容的三参数非局部相关泛函中使用这些补充。该泛函在分子热化学和动力学方面接近广泛使用的混合泛函的精度。DME 为与完全非局部局部交换兼容的实用、最少经验的非局部相关泛函提供了基础。
