article published yes P. Wirnsberger author D. Fijan author Anđela Šarić author bf63d406-f056-11eb-b41d-f263a6566d8b0000-0002-7854-2139 M. Neumann author C. Dellago author D. Frenkel author Using non-equilibrium molecular dynamics simulations, it has been recently demonstrated that water molecules align in response to an imposed temperature gradient, resulting in an effective electric field. Here, we investigate how thermally induced fields depend on the underlying treatment of long-ranged interactions. For the short-ranged Wolf method and Ewald summation, we find the peak strength of the field to range between 2 × 107 and 5 × 107 V/m for a temperature gradient of 5.2 K/Å. Our value for the Wolf method is therefore an order of magnitude lower than the literature value [J. A. Armstrong and F. Bresme, J. Chem. Phys. 139, 014504 (2013); J. Armstrong et al., J. Chem. Phys. 143, 036101 (2015)]. We show that this discrepancy can be traced back to the use of an incorrect kernel in the calculation of the electrostatic field. More seriously, we find that the Wolf method fails to predict correct molecular orientations, resulting in dipole densities with opposite sign to those computed using Ewald summation. By considering two different multipole expansions, we show that, for inhomogeneous polarisations, the quadrupole contribution can be significant and even outweigh the dipole contribution to the field. Finally, we propose a more accurate way of calculating the electrostatic potential and the field. In particular, we show that averaging the microscopic field analytically to obtain the macroscopic Maxwell field reduces the error bars by up to an order of magnitude. As a consequence, the simulation times required to reach a given statistical accuracy decrease by up to two orders of magnitude. American Institute of Physics2016 eng physical and theoretical chemistrygeneral physics and astronomy 0021-9606 1089-7690 1602.02734 2730599110.1063/1.4953036 14422 yes Wirnsberger, P., D. Fijan, Anđela Šarić, M. Neumann, C. Dellago, and D. Frenkel. “Non-Equilibrium Simulations of Thermally Induced Electric Fields in Water.” <i>The Journal of Chemical Physics</i>. American Institute of Physics, 2016. <a href="https://doi.org/10.1063/1.4953036">https://doi.org/10.1063/1.4953036</a>. Wirnsberger P, Fijan D, Šarić A, Neumann M, Dellago C, Frenkel D. Non-equilibrium simulations of thermally induced electric fields in water. <i>The Journal of Chemical Physics</i>. 2016;144(22). doi:<a href="https://doi.org/10.1063/1.4953036">10.1063/1.4953036</a> Wirnsberger, P., et al. “Non-Equilibrium Simulations of Thermally Induced Electric Fields in Water.” <i>The Journal of Chemical Physics</i>, vol. 144, no. 22, 224102, American Institute of Physics, 2016, doi:<a href="https://doi.org/10.1063/1.4953036">10.1063/1.4953036</a>. Wirnsberger, P., Fijan, D., Šarić, A., Neumann, M., Dellago, C., &#38; Frenkel, D. (2016). Non-equilibrium simulations of thermally induced electric fields in water. <i>The Journal of Chemical Physics</i>. American Institute of Physics. <a href="https://doi.org/10.1063/1.4953036">https://doi.org/10.1063/1.4953036</a> Wirnsberger P, Fijan D, Šarić A, Neumann M, Dellago C, Frenkel D. 2016. Non-equilibrium simulations of thermally induced electric fields in water. The Journal of Chemical Physics. 144(22), 224102. P. Wirnsberger, D. Fijan, A. Šarić, M. Neumann, C. Dellago, and D. Frenkel, “Non-equilibrium simulations of thermally induced electric fields in water,” <i>The Journal of Chemical Physics</i>, vol. 144, no. 22. American Institute of Physics, 2016. P. Wirnsberger, D. Fijan, A. Šarić, M. Neumann, C. Dellago, D. Frenkel, The Journal of Chemical Physics 144 (2016). 103802021-11-29T11:08:52Z2021-11-29T13:09:08Z