DISTRIBUTION OF LEVEL CURVATURES IN THE LOWEST LANDAU-LEVEL

An analysis of the statistics of level curvatures for a system exhibit ing the integer quantum Hall effect is presented. The curvatures k(n) are calculated numerically and their distribution P(k) is evaluated fo r energy eigenvalues E(n) belonging to insulating as well as to critic al states. In the insulating region it is found that P(0) = 0 and that P(lnk) depends on the system size, albeit weaker than linearly. There is no clear cut evidence that the distribution is log-normal. The dis tribution of curvatures corresponding to critical states is scale inva riant and appears to be way off the mark set by random matrix theory f or the unitary ensemble.