A perturbation theory is developed for treating a system of $n$ electrons in which the Hartree-Fock solution appears as the zero-order approximation. It is shown by this development that the first order correction for the energy and the charge density of the system is zero. The expression for the second-order correction for the energy greatly simplifies because of the special property of the zero-order solution. It is pointed out that the development of the higher approximation involves only calculations based on a definite one-body problem.

• Received 14 July 1934

DOI:https://doi.org/10.1103/PhysRev.46.618