Thermodynamic signatures of geometrical frustration in clusters.

We develop a comparative study of the extended Hubbard model on three-site clusters of triangular and linear geometries, searching for geometrical-frustration effects on thermodynamic properties. Using exact diagonalization, we evaluate physical quantities such as specific heat, entropy, and spin correlations as functions of temperature, varying interaction parameters and electron density. In particular, we highlight the existence of clear signatures of frustration in the thermal behavior of the electronic specific heat in triangular clusters, which allows us to suggest that specific-heat measurements may be an important experimental tool to detect geometrical frustration in correlated-electron systems.