High-Temperature Properties of the Half-Filled-Band Hubbard Model

Some important thermodynamic (specific-heat and magnetic-susceptibility) and dynamic (nuclear-spin---lattice relaxation) properties of the half-filled-band Hubbard model are calculated by a high-temperature expansion. In the strong-correlation limit Ut1, the expansion remains useful through the metal-insulator transition, breaking down only when βt becomes of order unity. Excellent agreement is found with exact calculations for finite linear chains and qualitative agreement is obtained with nuclear T₁ measurements in N-methylphenazinium---tetracyanoquinodimethan (NMP---TCNQ). Although these comparisons are made for linear chains, the theoretical predictions are made for three-as well as for one-dimensional systems.