A method for taking into account the long-range potential of atoms within the framework of the hard-sphere model is proposed. As shown, the thermodynamic quantities can be represented as a sum of three contributions—that of an ideal gas, the interaction of hard spheres, 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 the potential can be described within the scope of the self-consistent field model.