Diagrammatic complete active space perturbation theory: Calculations on benzene, N-2, and LiF

摘要

Second-order diagrammatic complete active space perturbation theory (D-CASPT2) is designed to have the best qualities from multireference Moller-Plesset (MRMP) theory, complete active space perturbation theory CASPT2, and the effective valence shell Hamiltonian H-v method, including possessing a linked diagram theorem (LDT) and an efficient second-order formalism. The accuracy of this method is illustrated through calculations of the electronic excitation energies of N-2 and benzene, the spectroscopic constants of the N-2 ground state, and the ionic-neutral avoided crossing in the potential curves of LiF. (C) 2000 American Institute of Physics. [S0021-9606(00)30508-6]. [References: 40]