Transition Pathways of Hydrogen Bond Exchanging Reaction in Pure Water

Hydrogen bond (H-bond) kinetic of pure water was explored extensively by molecular dynamic simulations. The non-H-bond configuration should be considered as a transition state with a short lifetime scale of 0.1 similar to 0.2 ps. Two types of transition states were found, by which the H-bond exchanging reactions took place. Distortion of one H-bond stimulates the H-bond exchanging reaction with the water molecule in the first coordination shell by path 1. Elongation of one H-bond stimulates the H-bond exchanging reaction with the water molecule in the second coordination shell by path 2. The possibility of two paths in the process of H-bond exchange varies with the temperature. The H-bond exchanging events usually take place between the over-coordinated and under-coordinated H-bond acceptors, as well as a proper geometric configurations required. The H-bond exchanging reactions play a key role in the translational and rotational motions of water molecules.