Abstract

In a polar fluid, strong temperature gradients can lead to molecular reorientation and polarisation, a phenomenon called ‘thermo-polarisation effect’. Recently Bresme and co-workers reported the establishment of an electrostatic field in simulations of liquid water in the presence of strong temperature gradients. They were able to demonstrate that the fields so obtained are proportional to the temperature gradients as predicted by non-equilibrium thermodynamics. Motivated by their work, we investigated the dependence of the electric field on the underlying treatment of electrostatic interactions for the previously employed, short-ranged Wolf method and Ewald summation. By comparing the simulation results for both techniques, we found that the Wolf method performs well in equilibrium, but fails to reproduce the correct results in the non-equilibrium steady-state.

[1] F Bresme, A Lervik, D Bedeaux and S Kjelstrup, ‘Water polarization under thermal gradients’, Physical Review Letters, 101, 020602, 2008.

[2] J Armstrong and F Bresme, ‘Water polarization induced by thermal gradients: The extended simple point charge model (SPC/E)’, Journal of Chemical Physics, 139, 014504, 2013.