  A gas of atoms some of which are in excited electronic state is under
consideration. Since the lifetime of an excited state is to great extent larger
than the time required for establishing the equilibrium over translational
degrees of freedom the system possesses equilibrium properties. They are
determined essentially by many-particle resonance interactions that appear in
the system of identical differently excited atoms. The present paper contains
the results of numerical calculations dealing with the examination of virial
state equation and density expansion for canonical pair spatial distribution
function of the system in question with the accuracy up to three-particle
contributions. The obtained results permit to study the excited atoms influence
on gas-liquid phase transition and the excimer molecules formation in the gas
with excited atoms.
