Application of direct methods for crystal structure determination using strongly dynamical bulk electron diffraction

In recent work it was shown that dynamical diffraction effects on direct methods calculations can be taken into account, and that the effect of dynamical scattering is an approximate reconstruction of \1 - Psi(r) \, where Psi(r) is the complex electron exit wave. The present work examines these approximations in more detail using the channeling theory and empirical examples. Despite a dependence on thickness and structure in the general case, the approximations are well justified for structures that consist of well-defined atomic columns along the beam direction. An overview of the present minimum relative entropy direct methods algorithm is presented. (C) Elsevier Science Inc., 1999. All rights reserved.