  In this manuscript we study the liquid-solid coexistence of NaCl-type alkali
halides, described by interaction potentials such as Tosi-Fumi (TF), Smith-Dang
(SD) and Joung-Cheatham (JC), and compute their melting temperature (Tm) at 1
bar via three independent routes: 1) liquid/solid direct coexistence, 2)
free-energy calculations and 3) Hamiltonian Gibbs-Duhem integration. The
melting points obtained by the three routes are consistent with each other. The
calculated Tm of the Tosi-Fumi model of NaCl is in good agreement with the
experimental value as well as with other numerical calculations. However, the
other two models considered for NaCl, SD and JC, overestimate the melting
temperature of NaCl by more than 200 K. We have also computed the melting
temperature of other alkali halides using the Tosi-Fumi interaction potential
and observed that the predictions are not always as close to the experimental
values as they are for NaCl. It seems that there is still room for improvement
in the area of force-fields for alkaline halides, given that so far most models
are still unable to describe a simple yet important property such as the
melting point.
