Particular thermal properties of internal energy, entropy, specific heat capacity and pressure are indicated using static fluctuation approximation (SFA) for specified temperatures and densities where the interaction between particles is still valid. This ab initio

study starts initially from the most reliable krypton interatomic potential and develops with complementary SFA assumptions that depend mainly on substituting the localfield mean value instead of its operator, thus developing a numerical solution of a non

linear close set equation by iteration technique. The results are matched with the ideal gas and show a considerable sense.