title: Temperature inversion of the thermal polarization of water.
abstract: Temperature gradients polarize water, a nonequilibrium effect that may result in significant electrostatic fields for strong thermal gradients. Using nonequilibrium molecular dynamics simulations, we show that the thermal polarization features a significant dependence with temperature that ultimately leads to an inversion phenomenon, whereby the polarization field reverses its sign at a specific temperature. Temperature inversion effects have been reported before in the Soret coefficient of aqueous solutions, where the solution changes from thermophobic to thermophilic at specific temperatures. We show that a similar inversion behavior is observed in pure water. Microscopically, the inversion is the result of a balance of dipolar and quadrupolar contributions and the strong temperature dependence of the quadrupolar contribution, which is determined by the thermal expansion of the liquid.
authors.affiliation: Department of Chemistry, Imperial College, London SW7 2AZ, United Kingdom.
authors.forename: Jeff
authors.initials: J
authors.lastname: Armstrong
authors.affiliation: Department of Chemistry, Imperial College, London SW7 2AZ, United Kingdom.|Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Fernando
authors.initials: F
authors.lastname: Bresme