A simple theory whose forte has been the determination of structures and energy levels for large nonionic systems is found to be applicable to ionic systems when the effects of self-consistent charge transfer are incorporated. The theory confirms the LEED structural analyses for O, S, and Se on Ni(100) and S on Ni(111) as found by Demuth, Jepsen, and Marcus. Further, the atomic valence ionization energy shifts are in agreement with the surface oxide photoemission spectrum of Conrad, Ertl, Küppers, and Latta.