Pressure of fluids and solids composed of particles interacting with a short-range repulsive potential

A simple short range repulsive potential (SR), with an even smoother cut off than the Weeks-Chandler-Andersen (WCA)–Lennard–Jones potential, yields practically the same pressure, both in the fluid state and for the fcc solid, when the potential parameters are chosen such that the forces are the same at the distance where the the two potential curves are equal to $k_{B}T.\mathrm{}$ The comparison of the pressure for the SR and the WCA systems is based on molecular dynamics computer simulations. The fluid branch of the equation of state is rather well described by a modified Carnahan-Starling expression.