Thermodynamics for the two-impurity Kondo model

A numerical renormalization-group calculation of the magnetic susceptibility, entropy, and specific heat for the two-impurity Kondo model is reported. For illustrative impurity separations, the temperature dependence of the impurity-added contribution to the three properties is computed. The results are physically interpreted, special attention being given to the competition between the Ruderman-Kittel-Kasuya-Yosida interaction and the Kondo effect.