%0 Journal article
%A Lübben, Jens
%A Volkmann, Christian
%A Grabowsky, Simon
%A Edwards, Alison
%A Morgenroth, Wolfgang
%A Fabbiani, Francesca P. A.
%A Sheldrick, George M.
%A Dittrich, Birger
%T On the temperature dependence of H-U iso in the riding hydrogen model
%R 10.1107/S2053273314010626
%R 10.23689/fidgeo-2410
%J Acta Crystallographica Section A Foundations and Advances
%V 70
%N 4

%X 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.
%U http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/6723
%~  FID GEO-LEO e-docs