A new pair potential for liquid argon

Recently, the well-known point molecular attractive pair term, r-6 only asymptotically correct, has been modified (Lu J. X. and Marlow W. Ç. (1995) Phys. Rev. Lett. 74. 1724) by taking into account the effect of a molecular size through a parameter a characteristic of the atom. Our interest is to test this specific feature on the properties of argon in the liquid state. A new pair potential has been generated by adding to the short-range repulsion, modelled by an r-12 term. the attractive term proposed by Lu and Marlow. Parameters have been fitted on the excess internal energy for argon over a wide range of densities and temperatures. In order to achieve this test, the hybridized-mean spherical approximation (HMSA) integral equation has been used. The HMSA has proven to be very accurate to reproduce the structure and the thermodynamics self-consistently. Structural and thermodynamic results with the new pair potential are in very good agreement with the experiments as well as simulation data