Recent experiments demonstrated the possibilities of modifying ground-state chemical reaction rates by placing an ensemble of molecules in an optical microcavity through a resonant coupling between the cavity mode and molecular vibrations. Typical VSC experiments operate in the absence of any light source. The VSC-induced rate constant suppression occurs under the resonance condition when the cavity frequency matches the molecular vibrational frequency, and only under the normal incidence when considering in-plane momentum inside a Fabry-Pérot cavity. In this work, we use quantum dynamics simulations and analytic theories to provide valuable insights into observed VSC phenomena, including the resonance behavior, the nonlinear change of the rate constant when increasing Rabi splitting, modification of both reactive enthalpy and entropy, and a reason why, with a very low barrier, there is a lack of the cavity modification. The analytic theory also exhibits the normal incidence condition and collective coupling effects.