In this paper the potential energy of the Lennard-Jones and Devonshire (LJD) model has been corrected to increase its PVT prediction abilities. The correction of potential energy is done in two ways (i) taking the coordination number as a function of temperature and volume to improve the second virial prediction ability and (ii) taking pair correlation effects into account to improve the phase transition prediction ability. The results of calculations indicate improvement both on PVT behavior in the above range of variation especially on the phase transition prediction ability in solid-liquid and vapor-liquid regions.