Molecular simulations of the thermal conductivity of liquid water using the TIP4P/Ice and TIP4P/2005 models

Abstract

Relying on the Green-Kubo linear response theory, the equilibrium molecular dynamics simulations are performed to estimate the thermal conductivity of liquid water. First, using two rigid TIP4P-like water models, the density of liquid water is determined under various temperature (250--350 K) and pressure (1--100 bar) conditions. With an appropriate density, the thermal conductivity of liquid water is then estimated from the heat flux auto-correlation function. In line with previous simulation studies, the thermal conductivities determined using two water models are found to be very close but higher than the experimental data. {\color{blue}Moreover, the power spectrum analysis and regression procedure are performed to extract the acoustic and optical-like/intramolecular modes shown in the heat flux auto-correlation function. Despite many limitations, the analytical expression for energy transfer times between neighboring water molecules well explains the rapid convergence of thermal conductivity as a result of the reduced optical-like contribution being compensated with the acoustic component.} In addition, the impacts of temperature and pressure on thermal conductivity of liquid water are also assessed.