Thermal Transport\nand Thermal Polarization of Water\nin the Supercooled Regime

The behavior of water in the deep supercooled regime\nhas attracted\nsignificant interest, motivated by the hypothesis of the second critical\npoint of water. Previous studies indicated the existence of a water\nanomaly, characterized by a minimum in the thermal conductivity of\nwater. Here, we employ nonequilibrium molecular dynamics computer\nsimulation and the TIP4P/2005 water force field to investigate the\nthermal conductivity of supercooled water targeting four different\nisobars, 1, 200, 700, and 1200 bar. We demonstrate using NEMD simulations\nthe existence of minima in thermal conductivity associated with the\nmaximum isothermal compressibility and the minimum speed of sound\nin water, hence establishing a firm connection with the second critical\npoint of liquid water. Moreover, we demonstrate that thermal gradients\npolarize supercooled water with a thermal polarization coefficient\nof several mV/K. We explain the thermal polarization effect using\na theoretical formulation introduced recently that connects the thermal\npolarization effect to the isobaric thermal expansion coefficient.