  We construct an integrable Hubbard model with impurity site containing spin
and charge degrees of freedom. The Bethe ansatz equations for the Hamiltonian
are derived and two alternative sets of equations for the thermodynamical
properties. For this study, the thermodynamical Bethe ansatz and the quantum
transfer matrix approach are used. The latter approach allows for a consistent
treatment by use of a finite set of non-linear integral equations. In both
cases, TBA and QTM, the contribution of the impurity to the thermodynamical
potential is given by integral expressions.
