Hydrogen bond cooperativity in simulated water: Time dependence analysis of pair interactions

Hydrogen bonding in water systems is investigated by introducing a new method to analyze the time dependence of pair-interaction data obtained from a molecular dynamics simulation of 216 ST2 F. H. Stillinger and A. Rahman, J. Chem. Phys. 60, 1545 (1974) water molecules at 280 K. This approach avoids the use of cutoff values and yields a more realistic bond population, whose distributions of geometric and energetic properties are reported as a function of the bond lifetimes. For the fraction of long-lived bonds, correlation among bond stability, molecular mobility, and local structure is elecited. Percolation analysis of HB network evidences cooperativity in the spatial distribution of bonds, which does not originate from proton polarizability of HB and/or from many-body terms of the interaction potentials since a rigid water model and pair potentials are used. These features can play a role in the anomalous properties of liquid water.