Here, ∆𝜈̅ 𝐻𝐵,0 is the HB blueshift at a reference distance 𝑑 0 , chosen as the point at which the Buckingham shape crosses zero. Further, 𝑓(𝜃) is the angular term in eq. 6 which modulates the contributions of the head-on and side-on distance dependences of eq. 4 and 5, respectively. We modelled the C≡N frequency for nitriles experiencing purely electrostatic perturbations, HBs with water, and HBs with methanol simultaneously as a function of electric field, HB distance, and HB angle, i.e., using eq. 2 with eq. 7 for the ∆𝜈̅ 𝐻𝐵 term. The resulting "𝜈̅ (𝐹 ⃗ , d, θ) model vs DFT" plot (Fig. ) shows that the VSE (eq. 1a) with the addition of eq. 7 recapitulates the DFT frequencies for purely electrostatic environments just as well as the VSE model alone (Fig. ) but significantly improves the recapitulatability in H-bonding environments. Fitting parameters for the model are reported in Table and Table . B: 2D heat plot of ∆𝜈̅ 𝐻𝐵 (𝑑, 𝜃) with water and methanol as HB donors according to the model in eq. 7. C: 2D heat plot of the residuals between modelled ∆𝜈̅ 𝐻𝐵 (𝑑, 𝜃) (see B) and ∆𝜈̅ 𝐻𝐵 from Fig. C and F (R 2 = 0.96 and RMSD = 2.4 cm -1 ).