Liquid-vapour equilibrium with double yukawa potential

A statistical mechanical based theory is developed for incorporating the long range correlations in the frame work of the first order perturbation theory to study the liquid-vapour equilibrium. The transition temperature and the liquid-vapour coexistence curves are found to depend considerably on the long range correlations and on the realistic radial distribution function. The calculated liquid-vapour equilibrium curves are in good agreement with the computer simulation results.