Calculation of the ground states of molecules with closed shells via Feynman diagrams

A Feynman-diagram calculation is performed for the ground-state energies of molecules of the XY_p type with closed electron shells. The first two orders in perturbation theory are considered.We are indebted to Dr. V. V. Tolmachev for proposing the topic and for substantial assistance in deriving the results, and also to Dr. U. I. Safronova for constant interest.