We use the exact correlation function of the density of energy levels in the magnetic field to evaluate persistent currents in mesoscopic metals. We also analyze the perturbation theory limit of the correlation function vis-a-vis the perturbation theory limit of the orbital response.

We extend our study of thermodynamics of a Kubo particle to temperatures smaller than the mean interlevel spacing. We obtain the distribution functions of spin susceptibility and heat capacity for Poisson and Wigner-Dyson level statistics. We evaluate the line shape of the Knight shift due to spin effects both in a single particle and for the ensemble average and compare it with orbital and spin-orbit contributions.

We argue that certain aspects of conventional thermodynamics are valid only for temperatures larger than the mean energy level spacing for a finite quantum fermion system (the Kubo particle) and evaluate its heat capacity and spin susceptibility.