  We use molecular simulation to construct equilibrium phase diagrams for two
recently introduced model materials with isotropic, soft-repulsive pair
interactions designed to favor diamond and simple cubic lattice ground states,
respectively, over a wide range of densities [Jain et al., Soft Matter 9 14
(2013)]. We employ free energy based Monte Carlo simulation techniques to
precisely trace the inter-crystal and fluid-crystal coexistence curves. We find
that both model materials display rich polymorphic phase behavior featuring
stable crystals corresponding to the target ground-state structures, as well as
a variety of other crystalline (e.g., hexagonal and body-centered cubic) phases
and multiple reentrant melting transitions.
