  A method for taking into account the long-range potential of atoms in the
framework of the hard-sphere model is proposed. It is shown that thermodynamic
quantities can be represented as a sum of three contribution: that of an ideal
gas, the interaction of hard sphere, and the long-range potential. In the
leading approximation on density, the corrections to the virial coefficient and
heat capacity due to the smooth component of the potential are calculated.
Attention is drawn to the fact that the effects determined by the long-range
part of of the potential can be described in the framework of the
self-consistent field model.
