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Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM)

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Netzel, Jeanette ; van Smaalen, Sander:
Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM).
In: Acta Crystallographica Section B. Bd. 65 (Oktober 2009) Heft 5 . - S. 624-638.
ISSN 2052-5206
DOI: https://doi.org/10.1107/S0108768109026767

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Abstract

Charge densities have been determined by the Maximum Entropy Method (MEM) from the high-resolution, low-temperature (T ≃ 20K) X-ray diffraction data of six different crystals of amino acids and peptides. A comparison of dynamic deformation densities of the MEM with static and dynamic deformation densities of multipole models shows that the MEM may lead to a better description of the electron density in hydrogen bonds in cases where the multipole model has been restricted to isotropic displacement parameters and low-order multipoles (lmax = 1) for the H atoms. Topological properties at bond critical points (BCPs) are found to depend systematically on the bond length, but with different functions for covalent C—-C, C—-N and C—-O bonds, and for hydrogen bonds together with covalent C—-H and N—-H bonds. Similar dependencies are known for AIM properties derived from static multipole densities. The ratio of potential and kinetic energy densities |V(BCP)|/G(BCP) is successfully used for a classification of hydrogen bonds according to their distance d(H⋅sO) between the H atom and the acceptor atom. The classification based on MEM densities coincides with the usual classification of hydrogen bonds as strong, intermediate and weak Jeffrey (1997). {An Introduction to Hydrogen Bonding}. Oxford University Press. MEM and procrystal densities lead to similar values of the densities at the BCPs of hydrogen bonds, but differences are shown to prevail, such that it is found that only the true charge density, represented by MEM densities, the multipole model or some other method can lead to the correct characterization of chemical bonding. Our results do not confirm suggestions in the literature that the promolecule density might be sufficient for a characterization of hydrogen bonds.

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Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Keywords: topological properties; hydrogen bonding; maximum entropy method; charge densities; peptides; amino acids
Institutionen der Universität: Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften > Lehrstuhl Kristallographie
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften > Lehrstuhl Kristallographie > Lehrstuhl Kristallographie - Univ.-Prof. Dr. Sander van Smaalen
Fakultäten
Fakultäten > Fakultät für Mathematik, Physik und Informatik
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
Eingestellt am: 10 Aug 2015 09:21
Letzte Änderung: 10 Aug 2015 09:21
URI: https://eref.uni-bayreuth.de/id/eprint/17847