Many-Body Approach to Electron Correlation in Atoms and Molecules

Abstract

Many-body perturbation theory (MBPT) is used to investigate the energy, wave function, and two-electron density matrix of a closed-shell atom or molecule when the initial approximation to the wave function is taken in the Hartree-Fock approximation. Since, as Kelly has found in his calculations using MBPT, certain classes of terms dominate in all orders of perterbation theory, models are investigated in which certain types of terms are summed to all orders of perturbation theory. The diagrams which are summed are explicitly chosen to provide results in the form of inhomogeneous integrodifferential equations which are as similar as possible to the models used by Kelly, Sinanoğlu, and Nesbet, thereby enabling some comparison to be made between these theories and indicating some of the corrections to them.