title: Dynamical aspects of intermolecular proton transfer in liquid water and low-density amorphous ices.
abstract: The microscopic dynamics of an excess proton in water and in low-density amorphous ices has been studied by means of a series of molecular dynamics simulations. Interaction of water with the proton species was modelled using a multistate empirical valence bond Hamiltonian model. The analysis of the effects of low temperatures on proton diffusion and transfer rates has been considered for a temperature range between 100 and 298 K at the constant density of 1 g cm(-3). We observed a marked slowdown of proton transfer rates at low temperatures, but some episodes are still seen at 100 K. In a similar fashion, mobility of the lone proton gets significantly reduced when temperature decreases below 273 K. The proton transfer in low-density amorphous ice is an activated process with energy barriers between 1-10 kJ/mol depending of the temperature range considered and eventually showing Arrhenius-like behavior. Spectroscopic data indicated the survival of both Zundel and Eigen structures along the whole temperature range, revealed by significant spectral frequency shifts.
authors.affiliation: Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, Building B5, Northern Campus UPC. Jordi Girona, 1-3, 08034 Barcelona, Catalonia, Spain.
authors.forename: Amani
authors.initials: A
authors.lastname: Tahat
authors.affiliation: Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, Building B5, Northern Campus UPC. Jordi Girona, 1-3, 08034 Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Martí
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D007053:Ice; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D011522:Protons; D011789:Quantum Theory; D014867:Water / Q000737:chemistry*
chemical_list: D007053:Ice; D011522:Protons; D014867:Water