  In the paper the thermodynamics of a cubic cluster with 8 sites at quarter
filling is characterized by means of exact diagonalization technique.
Particular emphasis is put on the behaviour of such response functions as
specific heat and magnetic susceptibility. The system is modelled with extended
Hubbard model which includes electron hopping between both first and second
nearest neighbours as well as coulombic interactions, both on-site and between
nearest-neighbour sites. The importance of hopping between second nearest
neighbours and coulombic interactions between nearest neighbours for the
temperature dependences of thermodynamic response functions is analysed. In
particular, the predictions of Schottky model are compared with the
calculations based on the full energy spectrum.
