Petrov Klára, Csóka József, Kállay Mihály
Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary.
HUN-REN-BME Quantum Chemistry Research Group, Műegyetem rkp. 3., H-1111 Budapest, Hungary.
J Phys Chem A. 2024 Aug 8;128(31):6566-6580. doi: 10.1021/acs.jpca.4c02822. Epub 2024 Jul 29.
The natural auxiliary function (NAF) approach is an approximation to decrease the size of the auxiliary basis set required for quantum chemical calculations utilizing the density fitting technique. It has been proven efficient to speed up various correlation models, such as second-order Møller-Plesset (MP2) theory and coupled-cluster methods. Here, for the first time, we discuss the theory of analytic derivatives for correlation methods employing the NAF approximation on the example of MP2. A detailed algorithm for the gradient calculation with the NAF approximation is proposed in the framework of the method of Lagrange multipliers. To assess the effect of the NAF approximation on gradients and optimized geometric parameters, a series of benchmark calculations on small and medium-sized systems was performed. Our results demonstrate that, for MP2, sufficiently accurate gradients and geometries can be achieved with a moderate time reduction of 15-20% for both small and medium-sized molecules.
自然辅助函数（NAF）方法是一种近似方法，用于减小利用密度拟合技术进行量子化学计算所需的辅助基组的大小。它已被证明能有效加速各种相关模型，如二阶莫勒-普列斯特定理（MP2）理论和耦合簇方法。在此，我们首次以MP2为例，讨论采用NAF近似的相关方法的解析导数理论。在拉格朗日乘数法的框架下，提出了一种使用NAF近似进行梯度计算的详细算法。为了评估NAF近似对梯度和优化几何参数的影响，对中小型体系进行了一系列基准计算。我们的结果表明，对于MP2，对于中小型分子，在适度减少15 - 20%计算时间的情况下，可以获得足够精确的梯度和几何结构。
