Asymmetric Hubbard chain at half-filling

The ground-state phase diagram of the one-dimensional asymmetric Hubbard model at half-filling is studied by means of a perturbation expansion in the large-U limit and White's density matrix renormalization-group method for various values of the couplings. We argue that the introduction of asymmetry in the hopping parameters is a relevant perturbation for any repulsive U and drives the system into an ordered N\'eel antiferromagnet. The transition belongs to the Kosterlitz-Thouless universality class.