Phase transitions in systems with extremely short-ranged attractions: A density-functional theory

We obtain the phase diagram of a classical simple system of interacting particles. We use the square-well model potential to study the effect of extremely short-ranged attractive interactions on the phase diagram. In particular, we focus the attention on the solid-solid transition recently reported in the literature [Bolhuis et al., Phys. Rev. Lett. 72, 2211 (1994)]. We use a functional-perturbation approximation for the free energy. The theory predicts a first-order transition between two solid phases with the same structure, in agreement with recent Monte Carlo simulations. A discussion about the mechanism responsible for this transition is also included.