  The disorder driven quantum Hall to insulator transition is investigated for
a two-dimensional lattice model. The Hall conductivity and the localization
length are calculated numerically near the transition. For uncorrelated and
weakly correlated disorder potentials the current carrying states are
annihilated by the negative Chern states originating from the band center. In
the presence of correlated disorder potentials with correlation length larger
than approximately half the lattice constant the floating up of the critical
states in energy without merging is observed. This behavior is similar to the
levitation scenario proposed for the continuum model.

Mesoscale and Nanoscale Physics