Hellmann Lars, Tölle Johannes, Niemeyer Niklas, Neugebauer Johannes
Theoretische Organische Chemie, Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149 Münster, Germany.
Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149 Münster, Germany.
J Chem Theory Comput. 2022 May 10;18(5):2959-2974. doi: 10.1021/acs.jctc.2c00131. Epub 2022 Apr 21.
Range-separated hybrid functionals making use of a smooth separation of the Coulomb operator in terms of the error function and its complement have proven to be a valuable tool for improving Kohn-Sham density functional theory (DFT) calculations. This holds in particular for obtaining accurate excitation energies from linear-response time-dependent DFT. Evaluating the long-range exchange contributions represents one of the most time-consuming tasks in such calculations. Prefitted auxiliary basis sets can be employed to speed up this step. Here, we present a way to generate auxiliary basis sets optimized to fit the long-range exchange contributions only, contrary to the common optimization strategies on the basis of the full Coulomb operator. For this purpose, we use the atomic Cholesky decomposition technique. The basis sets are generated on-the-fly using the specific range-separation parameter defined in the exchange-correlation functional. We obtain excitation energies and oscillator strengths which are of similar or better accuracy than those obtained with conventional resolution-of-the-identity auxiliary basis sets while drastically reducing the number of auxiliary functions required. This is demonstrated for the QUESTDB#5 benchmark set. In addition, we outline the benefits of this approach in sequences of calculations employing varying range-separation parameters, as is the case in the optimally tuned range-separation strategy. Finally, we illustrate the efficiency of this approach for real-world examples, namely, a chlorophyll tetramer from photosystem II and a carotenoid-porphyrin-C triad.
利用误差函数及其互补函数对库仑算符进行平滑分离的范围分离混合泛函，已被证明是改进Kohn-Sham密度泛函理论（DFT）计算的一种有价值的工具。这尤其适用于从线性响应含时DFT获得精确的激发能。评估长程交换贡献是此类计算中最耗时的任务之一。预拟合的辅助基组可用于加速这一步骤。在这里，我们提出了一种生成仅针对长程交换贡献进行优化的辅助基组的方法，这与基于完整库仑算符的常见优化策略相反。为此，我们使用原子Cholesky分解技术。基组是根据交换相关泛函中定义的特定范围分离参数即时生成的。我们获得的激发能和振子强度与使用传统的单位分解辅助基组获得的结果具有相似或更好的精度，同时大幅减少所需的辅助函数数量。这在QUESTDB#5基准集上得到了证明。此外，我们概述了这种方法在采用不同范围分离参数的一系列计算中的优势，这在最优调整范围分离策略中就是如此。最后，我们通过实际例子说明了这种方法的效率，即来自光系统II的叶绿素四聚体和类胡萝卜素 - 卟啉 - C三联体。
