Non-self-adjoint Schrodinger operators A which correspond to non-symmetric zero-range potentials are investigated. For a given A, the description of non-real eigenvalues, spectral singularities and exceptional points are obtained; the possibility of interpretation of A as a self-adjoint operator in a Krein space is studied, the problem of similarity of A to a self-adjoint operator in a Hilbert space is solved.

http://arxiv.org/abs/1309.5482
Mathematical Physics (math-ph); Spectral Theory (math.SP); Quantum Physics (quant-ph)