  The electrostatic interaction in ionic fluids is well-known to give rise to a
characteristic phase behavior and structure. Sometimes its long range is
proposed to single out the electrostatic potential over other interactions with
shorter ranges. Here the importance of the range for the phase behavior and the
structure of ionic fluids is investigated by means of grandcanonical Monte
Carlo simulations of the lattice restricted primitive model (LRPM). The
long-ranged electrostatic interaction is compared to various types of
short-ranged potentials obtained by sharp and/or smooth cut-off schemes.
Sharply cut off electrostatic potentials are found to lead to a strong
dependence of the phase behavior and the structure on the cut-off radius.
However, when combined with a suitable additional smooth cut-off, the
short-ranged LRPM is found to exhibit quantitatively the same phase behavior
and structure as the conventional long-ranged LRPM. Moreover, the
Stillinger-Lovett perfect screening property, which is well-known to be
generated by the long-ranged electrostatic potential, is also fulfilled by
short-ranged LRPMs with smooth cut-offs. By showing that the characteristic
phase behavior and structure of ionic fluids can also be found in systems with
short-ranged potentials, one can conclude that the decisive property of the
electrostatic potential in ionic fluids is not the long range but rather the
valency dependence.
