where the weighting factor 𝜔 k Γ 01 /(Γ 10 + Γ ′ 10 ) in the above expression takes a sharp maximum at 𝑘 ‖ = 0 and decays quickly when 𝑘 ‖ increases, because Γ ′ 10 increases quickly as 𝑘 ‖ increases. This means that for a 2D cavity, as used in all existing VSC experiments, the VSC-modified rate constant is still maximized around 𝜔 k (𝑘 ‖ = 0) = 𝜔 c = 𝜔 0 , fulfilling the normal incidence condition. Note that the above correction factor Γ 01 /(Γ 10 + Γ ′ 10 ) can also be applied to the 1D FP cavity but does not introduce any difference in Fig. , due to the van-Hove singularity in the DOS (see Eq. 22) which dominates the entire integral, forcing 𝒫 eff (𝜔 k ) → 𝑒 -𝛽ℏ𝜔 k (as 𝜏 ‖ → ∞ when 𝑘 ‖ = 0).