Kaupp Martin, Bahmann Hilke, Arbuznikov Alexei V
Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
J Chem Phys. 2007 Nov 21;127(19):194102. doi: 10.1063/1.2795700.
Local hybrid functionals with position-dependent exact-exchange admixture are a new class of exchange-correlation functionals in density functional theory that promise to advance the available accuracy in many areas of application. Local hybrids with different local mixing functions (LMFs) governing the position dependence are validated for the heats of formation of the extended G3/99 set, and for two sets of barriers of hydrogen-transfer and heavy-atom transfer reactions (HTBH38 and NHTBH38 databases). A simple local hybrid Lh-SVWN with only Slater and exact exchange plus local correlation and a one-parameter LMF, g(r)=b(tau(W)(r)tau(r)), performs best and provides overall mean absolute errors for thermochemistry and kinetics that are a significant improvement over standard state-of-the-art global hybrid functionals. In particular, this local hybrid functional does not suffer from the systematic deterioration that standard functionals exhibit for larger molecules. In contrast, local hybrids based on generalized gradient approximation exchange tend to give rise to nonintuitive LMFs, and no improved functionals have been obtained along this route. The LMF is a real-space function and thus can be analyzed in detail. We use, in particular, graphical analyses to rationalize the performance of different local hybrids for thermochemistry and reaction barriers.
具有位置依赖精确交换混合的局域杂化泛函是密度泛函理论中的一类新型交换关联泛函，有望在许多应用领域提高现有精度。针对扩展G3/99数据集的生成热以及两组氢转移和重原子转移反应的势垒（HTBH38和NHTBH38数据库），验证了具有不同控制位置依赖性的局域混合函数（LMF）的局域杂化泛函。一种仅包含斯莱特和精确交换加上局域关联以及单参数LMF（g(r)=b(tau(W)(r)tau(r))）的简单局域杂化泛函Lh-SVWN表现最佳，在热化学和动力学方面提供的总体平均绝对误差相较于标准的最先进全局杂化泛函有显著改善。特别是，这种局域杂化泛函不会出现标准泛函对于较大分子所表现出的系统性恶化。相比之下，基于广义梯度近似交换的局域杂化泛函往往会产生非直观的LMF，并且沿此路线尚未获得改进的泛函。LMF是一个实空间函数，因此可以进行详细分析。我们特别使用图形分析来合理化不同局域杂化泛函在热化学和反应势垒方面的性能。
