Effective potential for two-body interactions

A new kind of effective potential, which permits the calculation of the quantum equilibrium averages of configuration dependent observables in a classical-like way, is used for calculating the quantum pair correlation function of a two-body system. The main feature of this effective potential is the capability to fully account for the quantum harmonic effects, so it proves much more efficient than the analogous one defined by the Wigner expansion. Applications and comparisons with exact data are made for the Lennard-Jones interaction, with the characteristic parameters of helium atoms and hydrogen molecules.