Comparison of some multireference electronic structure methods in illustrative applications  

作　　者：SHEN Jun LI ShuHua 

机构地区：[1]School of Chemistry and Chemical Engineering,Key Laboratory of Mesoscopic Chemistry of Ministry of Education,Institute of Theoretical and Computational Chemistry,Nanjing University,Nanjing 210093,China

出　　处：《Science China Chemistry》2010年第2期289-296,共8页中国科学(化学英文版)

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 20625309 and 20833003);the National Basic Research Program (Grant No. 2004CB719901);the China Postdoctoral Science Foundation (Grant No. 200904501069)

摘　　要：The performances of several multireference electronic structure methods including complete active space self-consistent field (CASSCF)-based second-order perturbation theory (CASPT2), multireference configuration interaction with single and double excitations (MR-CISD), MR-CISD with the Davidson correction (MR-CISD+Q), and the CASSCF-based block-correlated coupled cluster method (CAS-BCCC4) we developed recently are compared by applying them to study several different chemical problems involving computation of ground state potential energy surfaces, the singlet-triplet gaps in diradicals, reaction barriers, and the excitation energies of low-lying excited states. Comparison with the results from other highly accurate theoretical methods or the available experimental data demonstrate that for all the problems studied, the overall performance of CAS-BCCC4 is competitive with that of MR-CISD+Q, and better than that of CASPT2 and MR-CISD methods. Thus the CAS-BCCC4 approach is expected to be a promising theoretical method for quantitative descriptions of the electronic structures of molecules with noticeable multireference character.The performances of several multireference electronic structure methods including complete active space self-consistent field (CASSCF)-based second-order perturbation theory (CASPT2), multireference configuration interaction with single and double excitations (MR-CISD), MR-CISD with the Davidson correction (MR-CISD+Q), and the CASSCF-based block-correlated coupled cluster method (CAS-BCCC4) we developed recently are compared by applying them to study several different chemical problems involving computation of ground state potential energy surfaces, the singlet-triplet gaps in diradicals, reaction barriers, and the excitation energies of low-lying excited states. Comparison with the results from other highly accurate theoretical methods or the available experimental data demonstrate that for all the problems studied, the overall performance of CAS-BCCC4 is competitive with that of MR-CISD+Q, and better than that of CASPT2 and MR-CISD methods. Thus the CAS-BCCC4 approach is expected to be a promising theoretical method for quantitative descriptions of the electronic structures of molecules with noticeable multireference character.

关 键 词：MULTIREFERENCE block correlated coupled cluster CASPT2 MR-CISD 

分 类 号：O641.1[理学—物理化学]