Inverse scattering with fixed-energy data

The Newton-Sabatier method for solving inverse scattering problem with fixed-energy phase shifts for a sperically symmetric potential is discussed. It is shown that this method is fundamentally wrong: in general it cannot be carried through, the basic ansatz of R.Newton is wrong: the transformation kernel does not have the form postulated in this ansatz, in general, the method is inconsistent, and some of the physical conclusions, e.g., existence of the transparent potentials, are not proved. A mathematically justified method for solving the three-dimensional inverse scattering problem with fixed-energy data is described. This method is developed by A.G.Ramm for exact data and for noisy discrete data, and error estimates for this method are obtained. Difficulties of the numerical implementation of the inversion method based on the Dirichlet-to-Neumann map are pointed out and compared with the difficulty of the implementation of the Ramm's inversion method.