Energy levels of the weakly interacting radicals

Energy levels of the weakly interacting radicals are estimated on the basis of planar methyl radical interaction as a model. These levels depend on the given separation r between the centers of mass. The appropriate Schrödinger equation is solved by using the Brillouin-Wigner series method. Analytical forms for the integrals used to estimate matrix elements are derived. The principle of total momentum conservation is strictly obeyed. Some energy levels cannot be estimated as a result of divergence.