Structure retrieval in HREM

A new iteration method for direct structure retrieval starting from the exit plane-wave function Ψ_e(r) is proposed and tested on models. The imaginary part of the potential cannot be retrieved. The effects of the limited resolution of Ψ_e(r) as well as neglect of high-order Laue-zone effects and the choice of the starting potential on the result are discussed. The procedure is found to be preferable to that based on the subsequent approximation method with respect to a higher convergence rate. It is shown that an error as low as 10% may be obtained for the real part of the retrieved potential up to |σV(r)t| < 5.