title: An effective energy gradient expression for divide-and-conquer second-order Møller-Plesset perturbation theory.
abstract: We recently proposed a linear-scaling evaluation scheme for the second-order Mo̸ller-Plesset perturbation (MP2) energy based on the divide-and-conquer (DC) method [M. Kobayashi, Y. Imamura, and H. Nakai, J. Chem. Phys. 127, 074103 (2007)]. In this paper, we propose an approximate but effective expression for the first derivative of the DC-MP2 energy. The present scheme evaluates the one- and two-body density matrices, which appear in the MP2 gradient formula, in the DC manner; that is, the entire matrix is obtained as the sum of subsystem matrices masked by the partition matrix. Therefore, the method requires solving only the local Z-vector equations. Illustrative applications to three types of systems, peptides, Si surface model, and delocalized polyenes, reveal the effectiveness of the present method.
authors: Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050, Japan. kobayashi@suou.waseda.jp
authors: Masato
authors: M
authors: Kobayashi
authors: Hiromi
authors: H
authors: Nakai