  We present a Monte Carlo simulation study of the phase behavior of
two-dimensional classical particles repelling each other through an isotropic
Gaussian potential. As in the analogous three-dimensional case, a
reentrant-melting transition occurs upon compression for not too high
temperatures, along with a spectrum of water-like anomalies in the fluid phase.
However, in two dimensions melting is a continuous two-stage transition, with
an intermediate hexatic phase which becomes increasingly more definite as
pressure grows. All available evidence supports the
Kosterlitz-Thouless-Halperin-Nelson-Young scenario for this melting transition.
We expect that such a phenomenology can be checked in confined monolayers of
charge-stabilized colloids with a softened core.
