Distributions of Hydrogen Bond Lifetimes in Instantaneous and Inherent Structures of Water

Various distribution functions of hydrogen bond lifetimes, used to describe the dynamics of breakage and formation of these bonds are calculated for a molecular dynamics model of water of 3456 molecules at 310 K. Quenched (inherent) structures are derived from instantaneous MD structures. Comparing the distribution functions from I and Q structures allows interpreting their characteristic features. The sharp peak at similar to 15 fs, which prevails in the most frequently used distributions, is ascribed to short-lived "false" H bonds which results from violations of hydrogen bonding criteria induced by dynamic intermolecular vibrations of molecules. A special type of distribution, proposed earlier [34], contains information not only on dynamics, but on true, or random, breaking of hydrogen bonds. The distributions reveal four different types of characteristic times which reflect different sides of H bond dynamics.