The real space method for dynamical electron diffraction calculations in high resolution electron microscopy: III. A computational algorithm for the electron propagation with its practical applications

Abstract

The real space description of the high energy electron diffraction as used for the simulation of high resolution electron microscope images is analysed with respect to its numerical performance. Recent arguments reported in the literature, which question the practical utility of the real space method, are refuted. It is shown that these arguments do not concern the idea of real space calculations in se but are caused by an inappropriate approximation for the real space electron propagator. In this work a new and proper algorithm for the propagator is introduced by which the method becomes numerically equivalent and competitive in calculation speed with the multislice method. Furthermore, a real space “patching” method is devised, by which the dynamical electron diffraction in extended areas such as for crystal defects can be calculated in patches, hereby avoiding artificial periodic continuation and removing the limitations imposed by the computer memory.