Perturbational view of inherent structures in water

The existence of accurately measured oxygen pair-correlation functions for liquid water suggests a natural form of linear perturbation theory for that substance. The unperturbed potential involves isotropically interacting molecules, and reproduces the measured oxygen-pair short-range order. Monte Carlo simulations in this theoretical context have been carried out for the unperturbed system and for the fully coupled system in the liquid state at 25 ^∘{}C. Inherent structures (potential-energy minima) have been generated and examined in both of these cases; they demonstrate that the directionality intrinsic to hydrogen bonding plays an important role in structurally stabilizing short-range order at the pair and higher-order correlation levels.