Temperature dependence of interatomic forces in the Thomas-Fermi approximation

A Thomas-Fermi cell model is used to study the temperature dependence of interatomic forces of normal-density matter and its effect on the equation of state. It is found that the substantial stiffening of the internuclear repulsions between the Fermi temperature and the temperature of complete ionization totally suppresses the configurational heat capacity of the nuclei over this temperature range, as though they had become a gas of hard spheres. When the atom finishes ionizing, the missing heat capacity reappears as a high-temperature anomaly. I suggest that this behavior occurs universally in real matter