Interorbital pairs in clean and impure superconductors

We consider two orbital superconductor with spin singlet inter-orbital pairs only. The calculations of the local and global properties of such superconductor have been presented with special attention to the features which distinguish such system from the typical BCS one. In particular, in clean system we have found the existence of critical interaction U necessary to induce superconducting transition and the asymmetry (with respect to the chemical potential) in the partial density of states. In the disordered system, in which the characteristics change from place to place, we have calculated local densities of states N( r-vector , E) and local values of the order parameters Δ( r-vector ). Both N( r-vector ,E) and δ( r-vector ) can be measured with help of scanning tunneling microscope.