SEARCH Articles Figures Tables First-order Perturbation Theory for a Non-degenerate Level Mixing of Non-Degenerate Orbitals— Second-Order Perturbations Non-degenerate coupled-oscillator CD Non-degenerate eigenvalues Non-degenerate ground state Non-degenerate orbitals Non-degenerate perturbation Non-degenerate plasma Non-degenerate vibrations Non-degenerated states Perturbation theory non-degenerate