Statistics of subgap states in superconductors with sign-changing order parameter

There is a strong theoretical reasoning in favor of the $s_{\pm}$ superconducting state in new iron-based superconductors. The order parameter in such a state has different signs in the electron and hole Fermi pockets. In this situation scattering between different pockets by impurities has pair-breaking effect and introduces states inside the gap which strongly influence low-temperature behavior of superconducting parameters. We solve numerically the two-band Bogolyubov equations for the $s_\pm$ superconductor and explore behavior of density of states and localization properties at different scattering parameters and concentration of impurities. We found that the commonly used self-consistent T-matrix approximation is incomplete and not very accurate in describing subgap states.