  Molecular dynamics simulations of aqueous electrolytes generally rely on
empirical force fields, combining dispersion interactions - described by a
truncated Lennard-Jones (LJ) potential - and electrostatic interactions -
described by a Coulomb potential computed with a long-range solver. Recently,
force fields using rescaled ionic charges (electronic continuum correction,
ECC), possibly complemented with rescaling of LJ parameters (electronic
continuum correction rescaled, ECCR), have shown promising results in bulk, but
their performance at interfaces has been less explored. Here we started by
exploring the impact of the LJ potential truncation on the surface tension of a
sodium chloride aqueous solution. We show a discrepancy between the numerical
predictions for truncated LJ interactions with a large cutoff and for
untruncated LJ interactions computed with a long-range solver, which can bias
comparison of force field predictions with experiments. Using a long-range
solver for LJ interactions, we then show that an ionic charge rescaling factor
chosen to correct long-range electrostatic interactions in bulk also describes
accurately image charge repulsion at the liquid-vapor interface, and that the
rescaling of LJ parameters in ECCR models - aimed at capturing local ion-ion
and ion-water interactions in bulk - also describes well the formation of an
ionic double layer at the liquid-vapor interface. Overall, these results
suggest that the molecular modeling of aqueous electrolytes at interfaces would
benefit from using long-range solvers for dispersion forces, and from using
ECCR models, where the charge rescaling factor should be chosen to correct
long-range electrostatic interactions.
