The Valiev-Plotnikov-Robinson-Bixon-Jortner model builds directly on the previous formalism, where the rate constant is expressed as Equation 39 and the coupling as Equation . As previously, the transition is between some initial electronic state in a zeroth-vibrational state to a final electronic state in an s th -vibrational state. However, now the theory diverges; if we assume that the relaxation width Γ ns depends only weakly on the vibrational quantum number, and that it is also much larger than the resonance energy defect, similarly noted by Plonikov , Equation 39 can be recast and simplified to :