On H-dynamics of supercooled water confined in nanoporous silica

Abstract We calculated the effect of temperature on the mean kinetic energy of the protons, Ke(H), in supercooled water confined in nanoporous silica using a quantum harmonic semi-empirical model. The results are in very good agreement with recently published deep inelastic neutron scattering (DINS) measurements taken at 210K and 250K. The calculated T-effect between 5K and 295K was found to be practically the same as that previously calculated for bulk H 2 O. We emphasize in this connection that the measurement of the total ( isotropic ) Ke(H) using the DINS technique cannot be used for distinguishing the liquid-liquid phase transition in super cooled water confined in nanoporous silica. Nonetheless, the possible occurrence of such a transition could be explored by looking for quantum competing effects between the Cartesian components of Ke(H), along and perpendicular to the hydrogen bond direction.