Discontinuous modulation functions and their application for analysis of modulated structures with the computing system JANA2006

0465103 - FZÚ 2017 RIV DE eng J - Journal Article
Petříček, Václav - Eigner, Václav - Dušek, Michal - Čejchan, Antonín
Discontinuous modulation functions and their application for analysis of modulated structures with the computing system JANA2006.
Zeitschrift fur Kristallographie-Crystalline Materials. Roč. 231, č. 5 (2016), s. 301-312. ISSN 2194-4946. E-ISSN 2196-7105
R&D Projects: GA MŠMT LO1603
Institutional support: RVO:68378271
Keywords : crystal structure analysis * Jana2006 * modulated structures
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.179, year: 2016

Discontinuous modulation functions called crenel and saw-tooth have been developed for description and refinement of strongly modulated crystal structures with abrupt changes of modulation parameters. In this article we explain how to recognize discontinuous modulations in a Fourier map and how to refine structures where crenel or saw-tooth functions are combined with additional secondary modulation. Three sets of functions suitable for such combination are presented: the traditional ortho-harmonics, and newly developed sets of Legendre polynomials and x-harmonics. Tiny differences between refine ments based on particular function sets are demonstrated using simulated as well as existing modulated structures.
Permanent Link: http://hdl.handle.net/11104/0263817