Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany.
J Chem Phys. 2017 Jul 14;147(2):024101. doi: 10.1063/1.4990413.
An efficient implementation of energy gradients and of hyperfine coupling constants in second-order Møller-Plesset perturbation theory (MP2) is presented based on our fully atomic orbital (AO)-based approach. For the latter, an unrestricted AO-based MP2 formulation is introduced. A reduction in the dependency of the computational efficiency on the size of the basis set is achieved by a Cholesky decomposition and the prefactor is reduced by the resolution-of-the-identity approximation. Significant integral contributions are selected based on distance-including integral estimates (denoted as QQR-screening) and its reliability as a fully controlled screening procedure is demonstrated. The rate-determining steps are shown via model computations to scale cubically in the computation of energy gradients and quadratically in the case of hyperfine coupling constants. Furthermore, a significant speed-up of the computational time with respect to the canonical formulation is demonstrated.
本文提出了一种基于完全原子轨道（AO）的方法，实现了第二阶Møller-Plesset 微扰理论（MP2）中能量梯度和超精细耦合常数的高效计算。对于后者，引入了一种非限制 AO 基的 MP2 公式。通过 Cholesky 分解和分辨率的身份近似，降低了计算效率对基集大小的依赖性。根据包含距离的积分估计（称为 QQR 筛选）选择显著的积分贡献，并证明了其作为完全可控筛选过程的可靠性。通过模型计算，显示了决定速率的步骤在能量梯度的计算中呈立方比例，在超精细耦合常数的计算中呈二次比例。此外，与标准公式相比，计算时间显著加快。
