  The low energy eigenmodes of the continuum QCD Dirac operator are extended,
but on the lattice, due to discretization effects, the Dirac operator can have
localized eigenmodes. These non-physical modes can introduce strong lattice
artifacts for observables that are sensitive to chiral symmetry, especially in
mixed action simulations. We study how these lattice artifacts depend on the
parameters of the overlap operator and their affect on the distribution on the
Dirac eigenmodes and the topological susceptibility.
