Comment on Exploring nature and predicting strength of hydrogen bonds: A correlation analysis between atoms-in-molecules descriptors, binding energies, and energy components of symmetry-adapted perturbation theory

We evaluate the correlation between binding energy (BE) and electron density rho(r) at the bond critical point for 28 neutral hydrogen bonds, recently reported by Emamian and co-workers (J. Comput. Chem., 2019, 40, 2868). As an efficient tool, we use local stretching force constant kHBa derived from the local vibrational mode theory of Konkoli and Cremer. We compare the physical nature of BE versus kHBa, and provide an important explanation for cases with significant deviation in the BE- kHBa relation as well as in the BE-rho(r) correlation. We also show that care has to be taken when different hydrogen bond strength measures are compared. The BE is a cumulative hydrogen bond strength measure while kHBa is a local measure of hydrogen bond strength covering different aspects of bonding. A simplified and unified description of hydrogen bonding is not always possible and needs an in-depth understanding of the systems involved.

Automated summary

The study evaluates the correlation between binding energy and electron density at the bond critical point for neutral hydrogen bonds, comparing the physical nature of these measures. It provides explanations for deviations in these correlations and highlights the need for caution when comparing different hydrogen bond strength measures. A simplified and unified description of hydrogen bonding is not always possible and requires a deep understanding of the systems involved.