物理化学学报2017，Vol.33Issue(6)：1130-1139,10.DOI:10.3866/PKU.WHXB201703221
完全活性空间组态相互作用能量的拟合和外推
Fitting and Extrapolation of Configuration Interaction Energies in Complete Active Space
摘要
Abstract
Configuration interaction calculation in complete active space is related to the numbers of active electrons and orbitals.However,configuration interaction energy is not a monotonically decreasing function of these two variables.Thus,the numbers of active electrons and orbitals are not proper variables to extrapolate the configuration interaction energy.In order to address this problem,we defined a new variable:maximum number of unoccupied orbitals in the complete active space.We performed a series of configuration interaction calculations on singlet,doublet,and triplet molecules,and simulated their ground state energies with the number of active electrons and the number of maximum unoccupied orbitals.The mean square root errors of these simulations were on the order of 104.The accuracy of the extrapolated energies was better than that of MP4 and than that of CCSD for small molecules.The extrapolated full configuration interaction energies were very close to the energy values of full configuration interactions.Furthermore,the extrapolated energies were exploited to optimize the bond distances of several diatomic molecules and to compute harmonic vibrational frequencies.Their accuracies were better than that of the complete active space self-consistent field.关键词
活性空间/活性电子/活性轨道/能量外推/键长/谐振频率Key words
Complete active space/Active electron/Active orbital/Energy extrapolation/Bond length/Harmonic vibrational frequency分类
化学化工引用本文复制引用
曹静思,陈飞武..完全活性空间组态相互作用能量的拟合和外推[J].物理化学学报,2017,33(6):1130-1139,10.基金项目
The project was supported by the National Natural Science Foundation of China (21173020,21473008).国家自然科学基金(21173020,21473008)资助项目 （21173020,21473008）
