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Rietveld refinement and structure verification using `Morse' restraints
Author(s) -
Bushmarinov Ivan S.,
Dmitrienko Artem O.,
Korlyukov Alexander A.,
Antipin Mikhail Yu.
Publication year - 2012
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/s0021889812044147
Subject(s) - rietveld refinement , periodic boundary conditions , bond length , asymmetry , molecular geometry , molecule , density functional theory , materials science , crystallography , basis (linear algebra) , computational chemistry , chemistry , molecular physics , mathematics , physics , crystal structure , geometry , boundary value problem , mathematical analysis , quantum mechanics
A new restraint scheme for Rietveld refinement based on Morse bond energy potential is introduced, in which the asymmetry of the Morse potential allows the refinement to `break' the incorrectly placed bonds. The analysis of bond‐length distributions at different values of restraint strength reveals a visible difference in behavior of wrong and correct structures, which can be detected using robust statistical methods. This fact is employed as a basis for a novel structure verification criterion. The approach is demonstrated on known difficult cases of acetolone and γ‐quinacridone and used for the Rietveld refinement of N ‐(6‐phenylhexanoyl)glycyl‐L‐tryptophanamide, an organic molecule of a potential anxiolytic containing 32 non‐H atoms and 14 single bonds. The results are verified using density functional theory calculations with periodic boundary conditions.