The spectrum of the two-dimensional Hubbard model at low filling
Centre de Recherches sur les Très Basses Températures,
CNRS, B.P. 166, F-38042 Grenoble Cédex 9, France
Accepted: 26 June 1996
The entire energy spectrum is calculated numerically for the two-dimensional Hubbard model on square lattices with four electrons varying the interaction strength U in a wide range. Taking all symmetries explicitly into account a level statistical analysis is performed on this strongly correlated 2D system. The level spacing distribution and the number variance exhibit a random matrix (GOE) behavior for all positive values of U, the latter however only up to a medium energy scale independent of U.
PACS: 05.45.+b – Theory and models of chaotic systems / 75.10.Jm – Quantized spin models / 74.20.-z – Theory
© EDP Sciences, 1996