Probing the accuracy and precision of Hirshfeld atom refinement with HARt interfaced with Olex2

Hirshfeld atom refinement (HAR) is a novel X-ray structure refinement technique that employs aspherical atomic scattering factors obtained from stockholder partitioning of a theoretically determined tailor-made static electron density. HAR overcomes many of the known limitations of independent atom...

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Vydané v:IUCrJ Ročník 5; číslo 1; s. 32 - 44
Hlavní autori: Fugel, Malte, Jayatilaka, Dylan, Hupf, Emanuel, Overgaard, Jacob, Hathwar, Venkatesha R., Macchi, Piero, Turner, Michael J., Howard, Judith A. K., Dolomanov, Oleg V., Puschmann, Horst, Iversen, Bo B., Bürgi, Hans-Beat, Grabowsky, Simon
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: England International Union of Crystallography 01.01.2018
Predmet:
anisotropic displacement parameters
Atomic structure
crystallographic software
Diffraction
Electron density
Graphical user interface
Hirshfeld atom refinement
Hydrogen
Hydrogen bonds
hydrogen-atom properties
Mathematical models
Modelling
multipole modelling
Neutron diffraction
Neutrons
Research Papers
Scattering
anisotropic displacement parameters
crystallographic software
hydrogen-atom properties
Hirshfeld atom refinement
multipole modelling
ISSN:2052-2525, 2052-2525
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Popis
Shrnutí:Hirshfeld atom refinement (HAR) is a novel X-ray structure refinement technique that employs aspherical atomic scattering factors obtained from stockholder partitioning of a theoretically determined tailor-made static electron density. HAR overcomes many of the known limitations of independent atom modelling (IAM), such as too short element–hydrogen distances, r ( X —H), or too large atomic displacement parameters (ADPs). This study probes the accuracy and precision of anisotropic hydrogen and non-hydrogen ADPs and of r ( X —H) values obtained from HAR. These quantities are compared and found to agree with those obtained from (i) accurate neutron diffraction data measured at the same temperatures as the X-ray data and (ii) multipole modelling (MM), an established alternative method for interpreting X-ray diffraction data with the help of aspherical atomic scattering factors. Results are presented for three chemically different systems: the aromatic hydrocarbon rubrene (orthorhombic 5,6,11,12-tetraphenyltetracene), a co-crystal of zwitterionic betaine, imidazolium cations and picrate anions (BIPa), and the salt potassium hydrogen oxalate (KHOx). The non-hydrogen HAR-ADPs are as accurate and precise as the MM-ADPs. Both show excellent agreement with the neutron-based values and are superior to IAM-ADPs. The anisotropic hydrogen HAR-ADPs show a somewhat larger deviation from neutron-based values than the hydrogen SHADE-ADPs used in MM. Element–hydrogen bond lengths from HAR are in excellent agreement with those obtained from neutron diffraction experiments, although they are somewhat less precise. The residual density contour maps after HAR show fewer features than those after MM. Calculating the static electron density with the def2-TZVP basis set instead of the simpler def2-SVP one does not improve the refinement results significantly. All HARs were performed within the recently introduced HARt option implemented in the Olex2 program. They are easily launched inside its graphical user interface following a conventional IAM.
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Current address: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, T6G 2G2, Canada.
ISSN:2052-2525
2052-2525
DOI:10.1107/S2052252517015548