Rapid Evaluation of Individual Hydrogen Bonding Energies in Linear Water Chains

A model is proposed to rapidly evaluate the individual hydrogen bonding energies in linear water chains. We regarded the two O―H bonds of a water molecule as two dipoles. The magnitude of the O―H bond dipole moment can be varied due to the other water molecules' presence. An analytic potential energy function, which explicitly contains the permanent dipole-dipole interactions, the polarization interactions, the van der Waals interactions and the covalent interactions, was therefore established. The individual hydrogen bonding energies in a series of linear water chains were evaluated via the analytic potential energy function and compared with those obtained from the CP-corrected MP2/aug-cc-pVTZ calculations. The results show that the analytic potential energy function not only can produce the individual hydrogen bonding energies as accurately as the CP-corrected MP2/aug-cc-pVTZ method, but is very efficient as well, demonstrating the model proposed is reasonable and useful. Based on the individual hydrogen bonding energies obtained, the hydrogen bonding cooperativity in the linear water chains was explored and the natures of the hydrogen bonding in these water chains were discussed.