On S-matrix of Schrodinger Operators with Non-Symmetric Zero-Range   Potentials
  Non-self-adjoint Schrodinger operators which correspond to non-symmetric zero-range potentials are investigated. We show that various properties of these operators (eigenvalues, exceptional points, spectral singularities and the property of similarity to a self-adjoint operator) are completely determined by poles of the corresponding S-matrix. 
P. A. Cojuhari, A. Grod and S. Kuzhel
math-ph math.MP math.SP