Journal ArticleDOI
Redetermination, invariom‐model and multipole refinement of l‐ornithine hydrochloride
TLDR
Cruickshank's diffraction-component precision index and Stevens & Coppens suitability factor are discussed and the resulting electron densities on a grid were compared.Abstract:
The structure of l-ornithine hydrochloride, C5H13N2O_2^+Cl−, has been redetermined at 100 K by single-crystal X-ray diffraction within a project that aims to generate accurate bond-distance restraints for the invariom refinement of proteins. The high-resolution data were subject to an invariom and a multipole refinement, and the resulting electron densities on a grid were compared. Improvements in the conventional R factor obtained by multipole modelling were smaller than in other structures containing solely the elements CHNO owing to Cl core scattering. Cruickshank's diffraction-component precision index and Stevens & Coppens suitability factor are discussed.read more
Citations
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Hydrogen atoms can be located accurately and precisely by x-ray crystallography
TL;DR: It is shown that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation.
Journal ArticleDOI
An improved experimental databank of transferable multipolar atom models--ELMAM2. Construction details and applications.
Sławomir Domagała,Sławomir Domagała,Bertrand Fournier,Dorothee Liebschner,Benoit Guillot,Christian Jelsch +5 more
TL;DR: The deformation electron densities, electrostatic potentials and interaction energies calculated for several tripeptides and aromatic molecules are calculated using ELMam2 electron-density parameters and compared with the former ELMAM database and density functional theory calculations.
Journal ArticleDOI
Transferability of Multipole Charge Density Parameters for Supramolecular Synthons: A New Tool for Quantitative Crystal Engineering
TL;DR: In this paper, the modularity of the supramolecular synthon is used to obtain transferability of charge density derived multipolar parameters for structural fragments, thus creating an opportunity to derive charge density maps for new compounds.
Journal ArticleDOI
Structural analysis and multipole modelling of quercetin monohydrate--a quantitative and comparative study.
TL;DR: This quantitative and comparative study shows that in the absence of high-resolution diffraction data, the database transfer approach can be applied to the multipolar electron density features very accurately.
Journal ArticleDOI
Extending the supramolecular synthon based fragment approach (SBFA) for transferability of multipole charge density parameters to monofluorobenzoic acids and their cocrystals with isonicotinamide: importance of C-H···O, C-H···F, and F···F intermolecular regions.
Venkatesha R. Hathwar,Tejender S. Thakur,Ritesh Dubey,Mysore S. Pavan,Tayur N. Guru Row,Gautam R. Desiraju +5 more
TL;DR: This study shows that the SBFA method is generally applicable to generate charge density maps using information from multiple intermolecular regions.
References
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Journal ArticleDOI
On enantiomorph‐polarity estimation
TL;DR: In this article, the behaviour of the Rogers's η parameter for enantiomorph-polarity estimation is examined theoretically and experimentally on simulated intensity data for seven well-assorted compounds.
Journal ArticleDOI
The Analytical Calculation of Absorption in Multifaceted Crystals
R. C. Clark,J. S. Reid +1 more
TL;DR: In this paper, the exact analytic method of evaluating the absorption during scattering in multifaceted convex crystals is developed in a way that permits efficient computation, and a fast and accurate algorithm is given for finding the Howells polyhedra whose determination is fundamental to the analytic method.
Journal ArticleDOI
Testing aspherical atom refinements on small-molecule data sets
N. K. Hansen,Philip Coppens +1 more
TL;DR: In this paper, a generalized aspherical-atom formalism is used to refine X-ray data on silicon, tetracyanoethylene, p-nitropyridine N-oxide and ammonium thiocyanate.
Journal ArticleDOI
Can X‐ray data distinguish bonding effects from vibrational smearing?
TL;DR: In this article, the success of this separation can be tested by comparison of the vibration ellipsoids of bonded atom pairs, which should have equal amplitudes in the bond direction.