On the temperature dependence of H-Uiso in the riding hydrogen model
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Date
2014-07
Journal Title
Journal ISSN
Volume Title
Publisher
Acta Crystallographica
Abstract
The temperature dependence of H-Uiso in N-acetyl-L-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-Uiso below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found. © International Union of Crystallography
Description
Keywords
Hydrogen, Neutron diffraction, X-ray detection, Synchrotron radiation, Electrons, Experiment planning
Citation
Lubben, J., Volkmann, C., Grabowsky, S., Edwards, A., Morgenroth, W., Fabbiani, F. P. A., Sheldrick, G. M., & Dittrich, B. (2014). On the temperature dependence of H-Uiso in the riding hydrogen model. Acta Crystallographica Section A: Foundations and Advances, 70(4), 309-316. doi:10.1107/S2053273314010626