Green's operator for Hamiltonians with Coulomb plus polynomial   potentials
  The Hamiltonian of a Coulomb plus polynomial potential on the Coulomb-Sturmian basis has an infinite symmetric band-matrix structure. A band matrix can always be considered as a block-tridiagonal matrix. So, the corresponding Green's operator can be given as a matrix-valued continued fraction. As examples, we calculate the Green's operator for the Coulomb plus linear and quadratic potential problems and determine the energy levels. 
E. Kelbert, A. Hyder, F. Demir, Z. T. Hlousek and Z. Papp