1. Ultrafast librational relaxation of H2O in liquid water
- Author
-
Universitat Politècnica de Catalunya. Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya. SIMCON - First-principles approaches to condensed matter physics: quantum effects and complexity, Petersen, Jakob, Möller, Klaus Braagaard, Rey Oriol, Rosendo, Hynes, James T., Universitat Politècnica de Catalunya. Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya. SIMCON - First-principles approaches to condensed matter physics: quantum effects and complexity, Petersen, Jakob, Möller, Klaus Braagaard, Rey Oriol, Rosendo, and Hynes, James T.
- Abstract
The ultrafast librational (hindered rotational) relaxation of a rotationally excited H2O molecule in pure liquid water is investigated by means of classical nonequilibrium molecular dynamics simulations and a power and work analysis. This analysis allows the mechanism of the energy transfer from the excited H2O to its water neighbors, which occurs on a sub-100 fs time scale, to be followed in molecular detail, i.e., to determine which water molecules receive the energy and in which degrees of freedom. It is found that the dominant energy flow is to the four hydrogen-bonded water partners in the first hydration shell, dominated by those partners’ rotational motion, in a fairly symmetric fashion over the hydration shell. The minority component of the energy transfer, to these neighboring waters’ translational motion, exhibits an asymmetry in energy reception between hydrogen-bond-donating and -accepting water molecules. The variation of the energy flow characteristics with rotational axis, initial rotational energy excitation magnitude, method of excitation, and temperature is discussed. Finally, the relation of the nonequilibrium results to equilibrium time correlations is investigated., Postprint (published version)
- Published
- 2013