Hydrogen bond lifetime distributions in computer-simulated water

Various hydrogen bond lifetime distribution functions, used to describe the breaking and formation dynamics of these bonds in a computer experiment, are examined and relationships between them are found. The procedures for calculating these functions by the molecular dynamics method are described and the results for water models of 3456 molecules at 310 K are reported. The peak of short-lived spurious H-bonds, which results from short-time violations of hydrogen bonding criteria induced by dynamic intermolecular vibrations of molecules, prevails in the types of distributions most often referred to in the literature. A special distribution that appears to have not been used before is proposed. Along with short-lived bonds, it manifests long-lived ones whose lifetime is determined by the genuine, or random, hydrogen bond breaking rather than by dynamic. A technique to exclude dynamic effects and reveal the genuine H-bond breaking is proposed. This allows the evaluation of the average lifetime of "true" H-bonds that turns out to exceed 3 ps.