The above FGR expression, although quantitatively less accurate, can already be used to qualitatively understand the resonant behavior of the VSC-modified rate profiles in Fig. and Fig. , which gives rise to a maximum rate enhancement when ω c = ω 0 . With this simple FGR rate, we can also understand the observed scaling relation of k VSC ∝ η 2 c (Fig. ), as well as the basic trend that k VSC → 0 when τ c = 1/α → 0. As such, the FGR expression in Eq. 54 and its simpler limit in Eq. 55 provide a resonant VSC theory that can explain most of the numerical results in our work. To the best of our knowledge, this is the first analytic theory to explain the resonance enhancement of the VSC rate constant for an electronically adiabatic reaction. Despite its success in terms of explaining all basic trends of the VSC-modified rate constant (as shown in Fig. ), the current expression overestimates the absolute rate constant by a factor of 2.5. Future work is needed to develop a more quantitatively accurate rate constant for VSC-modified chemistry, as well as for the stronger light-matter coupling regime (η c > 0.05) and for the lossless case (τ c > 200 fs).