화학공학소재연구정보센터
Journal of Chemical Physics, Vol.100, No.7, 5080-5092, 1994
Many-Body Theory of Exchange Effects in Intermolecular Interactions - Density-Matrix Approach and Applications to He-F-, He-HF, H2-HF, and Ar-H2 Dimers
The first-order exchange energy for the interactions of closed-shell many-electron systems is expanded as a perturbation series with respect to the Muller-Plesset correlation potentials of the monomers. Explicit orbital formulas for the leading perturbation corrections are derived applying a suitable density matrix formalism. The numerical results obtained using the Moller-Plesset perturbation expansion, as well as nonperturbative, coupled-cluster type procedure, are presented for the interactions of He-F-, He-HF, H-2-HF, and Ar-H-2. It is shown that the correlation part of the first-order exchange energy increases the uncorrelated results by 10% to 30% for the investigated range of configurations. The analysis of the total interaction energies for selected geometries of these systems shows that at the present level of theory the symmetry-adapted perturbation approach correctly accounts for major intramonomer correlation effects and is capable to accurately reproduce the empirical potential energy surfaces.