The Influence of Percolation in the generalized Chalker-Coddington Model
  We numerically investigate the influence of classical percolation on the quantum Hall localization-delocalization transition. This is accomplished within the framework of the generalized Chalker--Coddington network model which allows us to control the number of {\em classical} saddle points by setting the width $W$ of the saddle point distribution. It is found that increasing this width causes a new microscopic length scale to appear which depends on $W$ and scales with the exponent $X\approx 1.36$ which indicates a close connection to the classical percolation length $\xi$ and its exponent $\nu_p=4/3$. Furthermore, the influence of an increase in $W$ on the spectral statistics of the quasienergies of the network model is investigated. An effect similar to the increase of the potential correlation length in the Landau model is seen. 
Marcus Metzler (Toho University)