Integral equation theory study of the two dimensional SRSS model

The integral equation theory of liquids was used to study anomalies in the purely repulsive core-softened 2-dimensional system. The thermodynamics and structure was assessed and anomalous regions determined. In the model, the particles are repelling each other through an isotropic core-softened potential with two characteristics lengths. The first is a hard core with one diameter and the second a soft corona at larger distance. Integral equation theory, based on the Ornstein–Zernike equation, is a fast method to study phase diagrams and thermodynamics. Beside the Ornstein–Zernike that connects total and director correlation functions another relations is needed called closure relation which cannot be obtained in an exact form and it is always some approximation. Various approximations exist with each of its own advantages and disadvantages. In this work we extensively tested hyper-netted chain, Percus–Yevick, Kovalenko–Hirata, Rogers–Young, modified Verlet and soft mean spherical closure. Convergence domain was established for each closure. Rogers–Young Verlet closure gave best results for this model where it converges. • MD and integral equation theory studied particles with core-softened repulsion. • Density, diffusion and structural anomaly are determined. • Predictions of the IET is in reasonably good agreement with the simulation.