SPECIFIC-HEAT OF THE HALF-FILLED ONE-DIMENSIONAL HUBBARD-MODEL - FEYNMAN PATH-INTEGRAL SIMULATIONS

The Feynman path-integral quantum Monte Carlo (PI QMC) approach has be en employed to study the specific heat C of the one-dimensional (1D) h alf-filled Hubbard chain as a function of temperature. For not too str ong many-body interactions C exhibits a single maximum only. With incr easing correlation strength the C curve shows an intermediate minimum separating a sharp low-temperature maximum and a broad high-temperatur e profile. The first peak is caused by spin excitations and the high-t emperature values of C are determined by charge degrees of freedom. Th e contribution of both quantities to the net specific heat curve has b een quantified in the present theoretical setup. The specific heat dat a are interpreted with the aid of calculated charge fluctuations, prob abilities P-i(n) to find n = 2, 1, 0 electrons at the respective latti ce sites, a spin density wave (SDW) order parameter and the electronic chemical potential mu.