2024 - Sustainable Industrial Processing Summit
SIPS 2024 Volume 7. Lipkowski Intl. Symp / Physical Chemistry
| Editors: | F. Kongoli, J. Atwood, L. Barbour, G. Duca, R. Kuroda, A. Legocki, M. Zaworotko |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2024 |
| Pages: | 171 pages |
| ISBN: | 978-1-998384-16-7 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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QUANTUM CRYSTALLOGRAPHY
Krzysztof Woźniak1;1UNIVERSITY OF WARSAW, Warszawa, Poland;
Type of Paper: Regular
Id Paper: 55
Topic: 53
Abstract:
This is quite a paradox that more than a century after introduction of the spherical Independent Atom Model (IAM, 1914 [1]), 99.7% of all ca. 1.5mln known crystal structures have still been refined using IAM which suffers from severe methodological deficiencies. Far better results can be obtained when new approaches of Quantum Crystallography(QCr) utilising aspherical atomic scattering factors are applied. In short, QCr is crystallography beyond IAM.
In this contribution, I will present details of aspherical Hansen-Coppens [2] pseudoatom refinement of electron density and the main ideas of Hirshfeld Atom refinement. My lecture will be complemented by several examples of our QCr [3-9] studies including: (1) multipole refinement of electron density in crystals of minerals including minerals under pressure, (2) Hirshfeld Atom Refinement (HAR) of ice structures against X-ray, electron diffraction and neutron diffraction data, (3) HAR refinement of H-atom positions in small molecule organic compounds and hydrides, and, if I still have some time, I will present: (4) Experimental HAR studies of relativistic effects and electron correlation in gold derivatives.
A century after the Braggs, it is possible to obtain H-atom positions from X-ray diffraction studies which are equally reliable as those from neutron diffraction. It is also possible to get reliable positions of H-atoms in the closest neighborhood of very heavy atoms, to study tiny redistribution of electron density in minerals under pressure, or to estimate consequences of relativistic effects using X-ray diffraction data. So users of X-ray crystallography can do far better than just routinely refining poor IAM model against precise, accurate and very often very dear diffractometer/synchrotron/ XFEL X-ray data. QCr approaches can also improve quality of macromolecular studies, powder -S-ray diffraction results, PDF, XANES, EXAFS, CryoEM, electron diffraction etc. In consequence, one can improve scientific results and stimulate progress in all fields of science/technology/medicine which utilize structural and electronic results.