Phase diagram of the system with the repulsive shoulder potential in two dimensions: Density functional approach

•Melting scenarios of two dimensional repulsive shoulder potential systems are studied.•The phase diagram is calculated using the density functional theory of freezing.•We show that at low densities the system melts though continuous transition.•At high densities melting occurs through the first order transition.

In the framework of the density functional theory of freezing proposed in our previous works, we calculate the phase diagram of two-dimensional system of particles interacting through the repulsive shoulder potential. This potential consists of the hard core and repulsive shoulder of the larger radius. It is shown that at low densities the system melts through the continuous transition in accordance with the Kosterlitz–Thouless–Halperin–Nelson–Young (KTHNY) scenario, while at high densities the conventional first order transition takes place.