Supercritical fluid of particles with a Yukawa potential: A new approximation for the direct correlation function and the Widom line

We propose an approximation of a direct correlation function corresponding to the linearization with respect to ${-}\beta\phi(r)$ of a generalized mean spherical approximation for a hard-core multi-Yukawa system of particles. We use the results to study the behavior of maximums of thermodynamic response functions in the supercritical region of a fluid with a two-term Yukawa potential imitating the Lennard-Jones potential.