[4]. The current numerically exact results predict that there will be a turnover of the rate constant as one increases the cavity lifetime τ c . As the cavity lifetime τ c increases, the VSC effect will increase first, which agrees with the analytic FGR theory. When further increasing the τ c , the numerically exact simulation suggests that the cavity modification effects decay to zero, and the analytic FGR theory failed to predict this trend. On the other hand, both numerical results and the analytic FGR theory predict that the cavity effect will diminish when τ c → 0 for a very lossy cavity.