Ni Zhigang, Wang Yuqi, Li Wei, Pulay Peter, Li Shuhua
School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Institute of Theoretical and Computational Chemistry , Nanjing University , Nanjing 210023 , P. R. China.
Department of Chemistry and Biochemistry , University of Arkansas , Fayetteville , Arkansas 72701 , United States.
J Chem Theory Comput. 2019 Jun 11;15(6):3623-3634. doi: 10.1021/acs.jctc.9b00259. Epub 2019 May 31.
An efficient analytical energy gradient algorithm for the cluster-in-molecule (CIM) second order Møller-Plesset perturbation theory (MP2) method is presented. In our algorithm, the gradient contributions from the nonseparable term of the two-body density matrix on a given atom is extracted from calculations on a cluster constructed for this atom. The other terms in the CIM-MP2 energy gradient expression are evaluated by constructing the density matrices of the whole system with the contributions from all clusters constructed. For basis sets with diffuse functions, tight CIM parameters are necessary to obtain accurate gradients. Benchmark calculations show that the CIM-MP2 method can accurately reproduce the conventional MP2 gradients and geometries for larger systems. The optimized structure of a 174-atom oligopeptide using the CIM-MP2 method with the cc-pVDZ basis set is in good agreement with the corresponding crystal structure. The present CIM-MP2 gradient program can be used for optimizing the geometries of large systems with hundreds of atoms on ordinary workstations.
提出了一种用于分子团簇中二阶莫勒-普列斯塞微扰理论（MP2）方法的高效解析能量梯度算法。在我们的算法中，给定原子上两体密度矩阵不可分离项的梯度贡献是从为该原子构建的团簇计算中提取的。CIM-MP2能量梯度表达式中的其他项通过用所有构建团簇的贡献构建整个系统的密度矩阵来评估。对于具有弥散函数的基组，紧密的CIM参数对于获得准确的梯度是必要的。基准计算表明，CIM-MP2方法可以准确地再现较大体系的传统MP2梯度和几何结构。使用具有cc-pVDZ基组的CIM-MP2方法对一个174原子的寡肽进行优化后的结构与相应的晶体结构吻合良好。当前的CIM-MP2梯度程序可用于在普通工作站上优化具有数百个原子的大体系的几何结构。
