title: Estimating temperature-dependent anisotropic hydrogen displacements with the invariom database and a new segmented rigid-body analysis program.
abstract: Invariom partitioning and notation are used to estimate anisotropic hydrogen displacements for incorporation in crystallographic refinement models. Optimized structures of the generalized invariom database and their frequency computations provide the information required: frequencies are converted to internal atomic displacements and combined with the results of a TLS (translation-libration-screw) fit of experimental non-hydrogen anisotropic displacement parameters to estimate those of H atoms. Comparison with TLS+ONIOM and neutron diffraction results for four example structures where high-resolution X-ray and neutron data are available show that electron density transferability rules established in the invariom approach are also suitable for streamlining the transfer of atomic vibrations. A new segmented-body TLS analysis program calledAPD-Toolkithas been coded to overcome technical limitations of the established programTHMA. The influence of incorporating hydrogen anisotropic displacement parameters on conventional refinement is assessed.
authors.affiliation: Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Lübben
authors.affiliation: Bruker-AXS SAS, 4 Allée Lorents, F-77447 Marne-la-Vallée, France.
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Bourhis
authors.affiliation: Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany ; Heinrich-Heine Universität Düsseldorf, Anorganische Chemie und Strukturchemie, Universitätsstrasse 1, Gebäude 26.42.01.21, 40225 Düsseldorf, Germany.
authors.forename: Birger
authors.initials: B
authors.lastname: Dittrich
keywords: anisotropic displacement parameters; generalized invariom database; segmented rigid-body analysis