  In this review we focus on the determination of phase diagrams by computer
simulation with particular attention to the fluid-solid and solid-solid
equilibria. The calculation of the free energy of solid phases using the
Einstein crystal and Einstein molecule methods are described in detail. It is
shown that for the hard spheres solid both methods yield the same results and
that free energies of solid phases present noticeable finite size effects.
Finite size corrections can be introduced, although in an approximate way, to
correct for the dependence of the free energy on the size of the system. The
computation of free energies of solid phases can be extended to molecular
fluids. The procedure to compute free energies of solid phases of water (ices
Ih, II, III, IV, V, VI, VII, VIII, IX, XI and XII) using the SPC/E and TIP4P
models will be described.Other methods to estimate the melting point of a
solid, as the direct fluid-solid coexistence or simulations of the free surface
of the solid will be discussed. It will be shown that the melting points of ice
Ih for several water models, obtained from these two methods and from free
energy calculations agree within statistical uncertainty. Phase diagram
calculations can help to improve potential models of molecular fluids; for
water, the TIP4P/2005 model can be regarded as an improved version of TIP4P. We
will also review some recent work on the phase diagram of the simplest ionic
model, the restricted primitive model. Although originally devised to describe
ionic liquids, the model is becoming quite popular to describe charged
colloids. Besides the possibility of obtaining fluid-solid equilibria for
simple protein models will be discussed. In these primitive models, the protein
is described by a spherical potential with certain anisotropic bonding sites.
