The role of the exchange interaction in the one-dimensional n-component hubbard model

Abstract

The commensurate p/q filled n-component Hubbard chain was investigated by bosonization and high-precision density-matrix renormalization-group analysis. It was found that depending on the relation between the number of components n, and the filling parameter q, the system shows metallic or insulating behavior, and for special fillings bond-ordered (dimerized, trimerized, tetramerized etc.) ground state develops in the insulating phase. A mean- field analysis shows that this bond ordering is a direct consequence of the spin-exchange interaction, which plays a crucial role in the one-parameter Hubbard model not only for infinite Coulomb repulsion, but for intermediate values as well.