One-particle dynamics in the Hubbard model at half-filling

A. T. Costa, M. T. Thomaz

The dynamical evolution of a two-site Hubbard model is derived in the presence of an uniform external magnetic field for a general initial state. The time evolution of the half-filled (two-particle) case has a complex behaviour. Under certain initial conditions, the average number of fermions in one-particle state, in the half-filled case, is not necessarily periodic, even though the magnetization remains periodic. The results obtained may be applied to study the magnetization and the transition dipole moment of the organic charge-transfer salts in the in-phase mode.

Yu. A. Izyumov, N. I. Chashchin

E. Szirmai, Jenő Sólyom

The one-dimensional SU$(n)$ Hubbard model is investigated using an analytical, perturbative renormalization-group treatment in the fermionic formulation of the model for $n>2$. It is found that in the half-filled case, the umklapp processes couple the spin and charge degrees of freedom and generate a finite gap for arbitrary finite positive $U$. This behavior is thus different from that at $1∕n$ filling, where there is one particle per site, in which case the dynamics of the two degrees of freedom can be separated and a critical ${U}_{\mathrm{c}}$ is needed for the Mott transition.

Andreas Schadschneider, J. Zittartz

Fabian H. L. Eßler, V. E. Korepin

We consider dynamical spin-spin correlation functions in the one-dimensional repulsive half-filled Hubbard model. We propose an exact expression for the two-spinon form factor of spin operators. We use this to derive the two-spinon contribution to the dynamical structure factor.

Yung‐Chung Chen, Hui-Chun Chien, Chih-Tin Shih