Nonextensive thermodynamics of the two - site Hubbard model 1

Thermodynamical and magnetic properties of the half-filled, two-site Hubbard model have been discussed within the framework of the Tsallis nonextensive statistics, in which the entropic index q plays an important role, the conventional Boltzman-Gibbs statistics being recovered in the limit of q = 1. The temperature dependence of the entropy, specific heat and magnetic susceptibility, and the magnetic-field dependence of the magnetization have been calculated for various q values. It has been demonstrated that calculated properties are significantly changed even for a small deviation of q from unity. The relevance of our calculation to nanoscale systems is also discussed.