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

Title data

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. Vol. 65 (October 2009) Issue 5 . - pp. 624-638.
ISSN 2052-5206
DOI: https://doi.org/10.1107/S0108768109026767

Official URL: Volltext

Abstract in another language

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.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: topological properties; hydrogen bonding; maximum entropy method; charge densities; peptides; amino acids
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Group Material Sciences > Chair Crystallography
Faculties > Faculty of Mathematics, Physics und Computer Science > Group Material Sciences > Chair Crystallography > Chair Crystallography - Univ.-Prof. Dr. Sander van Smaalen
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Group Material Sciences
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 10 Aug 2015 09:21
Last Modified: 10 Aug 2015 09:21
URI: https://eref.uni-bayreuth.de/id/eprint/17847