Many-Body Perturbation Theory for Molecules Based on a United Atom Model

Abstract

The linked-cluster many-body perturbation theory is developed for molecules using the united atom as a starting point. Specific application is made to hydrogen fluoride with neon as the united atom. The calculated energy for the molecule is found to be -100.4186 a.u. in excellent agreement with the experimental value of -100.4485 a.u. The theoretical correlation energy is found to be 92% of experiment. Satisfactory agreement is also obtained for the electric field at the fluorine nucleus.