10-04U

The ground state and thermodynamics of the spin-1/2 distorted diamond Ising-Hubbard chain with on-site Coulomb repulsion are studied. By means of the decoration-iteration transformation exact results for the free energy, entropy, specific heat, magnetizations of the Ising and Hubbard subsystems, and magnetic susceptibility are obtained. In the case of geometric frustration the effect of the Coulomb repulsion on the ground state, the field and temperature dependencies of the magnetization, magnetic susceptibility, specific heat is analyzed. The strong repulsion leads to the appearance of an additional high-temperature maximum of the specific heat. Independently of the presence of the repulsion, the specific heat may have two low-temperature peaks.