SEARCH Articles Figures Tables Energy second Ordering energy Perturbation energy Perturbation energy, second-order Perturbation order Perturbation theory Schrodinger Perturbation theory energy Perturbation theory, Rayleigh-Schrodinge Perturbed energy Rayleigh theory Rayleigh-Schrodinger Rayleigh-Schrodinger perturbation Rayleigh-Schrodinger perturbation theory Rayleigh-Schrodinger theory Schrodinger theory Second-order energy Second-order theory