and the light-matter coupling term explicitly vanishes due to the fact that ⟨∆μ⟩ HF = ⟨μ -⟨μ⟩ HF ⟩ HF = 0. Using this strategy, the light-matter coupling term ⟨λ • μ⟩ HF • (â † + â) resulting from the ĤPF (in Eq. 119) no longer explicitly shows up in Eq. 123, and the implicit coupling between molecule and cavity is now carried through