Effect of the reference choice on the contribution of molecular dipoles to the local electric potential

The profile of the electric potential at interfaces is often employed in discussions of classical molecular dynamics models. However, in contrast to the total potential, the contribution of molecular dipoles to the potential depends on the choice of an arbitrary reference point within molecules. We show both analytically and in a simulation how this choice affects the dipole contribution in the bulk. The analytic derivation pinpoints the origin of the changes in the dipole contribution. The simulation verifies the analytic expression and shows the exact influence of the chosen molecular reference. This work highlights the inherent issues of the dipole contribution to the electric potential.