Nearly universal crossing point of the specific heat curves of hubbard models

Abstract

A nearly universal feature of the specific heat curves (Formula presented) vs T for different U of a general class of Hubbard models is observed. That is, the value (Formula presented) of the specific heat curves at their high-temperature crossing point (Formula presented) is almost independent of lattice structure and spatial dimension (Formula presented) with (Formula presented) This surprising feature is explained within second-order perturbation theory in U by identifying two small parameters controlling the value of (Formula presented) the integral over the deviation of the density of states (Formula presented) from a constant value, characterized by (Formula presented) and the inverse dimension (Formula presented) © 1999 The American Physical Society.