Iterative structure retrieval techniques in HREM: a comparative study and a modular program package

Abstract

A retrieval technique for crystal structures using high‐resolution electron microscopy is presented. The inversion of the complex structure‐to‐image relation is performed by numerical optimization of the configuration space of object models. Unlike structure refinement in X‐ray crystallography, the method operates on unknown defect structures on a nanometre scale. The diversity of crystal defects examined and the differences in microscope types and alignment conditions makes it necessary to adapt the basic algorithm to a broad variety of needs resulting in a modular program package for general use. New developments, such as a real space slice function calculation, problem adapted optimization strategies, and finally an examination of iterative matching of image series and exit wavefunctions are presented.