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Using FOCUS to solve zeolite structures from three‐dimensional electron diffraction data
Author(s) -
Smeets Stef,
McCusker Lynne B.,
Baerlocher Christian,
Mugnaioli Enrico,
Kolb Ute
Publication year - 2013
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889813014817
Subject(s) - electron diffraction , diffraction , electron crystallography , reflection (computer programming) , focus (optics) , direct methods , optics , scattering , electron , crystallography , powder diffraction , materials science , physics , computer science , chemistry , quantum mechanics , programming language
The program FOCUS [Grosse‐Kunstleve, McCusker & Baerlocher (1997). J. Appl. Cryst. 30 , 985–995] was originally developed to solve zeolite structures from X‐ray powder diffraction data. It uses zeolite‐specific chemical information (three‐dimensional 4‐connected framework structure with known bond distances and angles) to supplement the diffraction data. In this way, it is possible to compensate, at least in part, for the ambiguity of the reflection intensities resulting from reflection overlap, and the program has proven to be quite successful. Recently, advances in electron microscopy have led to the development of automated diffraction tomography (ADT) and rotation electron diffraction (RED) techniques for collecting three‐dimensional electron diffraction data on very small crystallites. Reasoning that such data are also less than ideal (dynamical scattering, low completeness, beam damage) and that this can lead to failure of structure solution by conventional direct methods for very complex zeolite frameworks, FOCUS was modified to accommodate electron diffraction data. The modified program was applied successfully to five different data sets (four ADT and one RED) collected on zeolites of different complexities. One of these could not be solved completely by direct methods but emerged easily in the FOCUS trials.