We extracted values for the exponential decay constant (b) and the exponent of the power-term (n2) of b ≈ 3.1 Å -1 and n2 ≈ -8.2. The decay constant is in a similar range as values used for intermolecular O---C, C---H, and O---H interactions in force fields (a range of 2.7 -4.6 Å -1 ), suggesting that HB blueshifts in side-on HBs originate from Pauli repulsion; this finding is consistent with previous studies. The power law in the Buckingham potential is typically used with an exponent of -6 to account for attractive dipole -induced dipole interactions. However, the original form of the Buckingham potential also included a d -8 -term accounting for attractive quadrupole -induced quadrupole interactions. When fitting the data in Fig. using two power-terms, both exponents converged to the same value of ~ -8.2, indicating this value is fairly robust; as such, we tentatively assign negative contributions to ∆𝜈̅ 𝐻𝐵 (i.e., redshifts) to induced higher-order multipole interactions.