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Modern charge density studies: the entanglement of experiment and theory

Type of publication Peer-reviewed
Publikationsform Review article (peer-reviewed)
Publication date 2013
Author Macchi Piero,
Project Properties of metal-organic materials from accurate electron density determination
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Review article (peer-reviewed)

Journal Crystallographic Reviews
Volume (Issue) 19
Page(s) 58 - 101
Title of proceedings Crystallographic Reviews

Open Access

Type of Open Access Repository (Green Open Access)


This tutorial review article is intended to provide a general guidance to a reader interested to learn about the methodologies to obtain accurate electron density mapping in molecules and crystalline solids, from theory or from experiment, and to carry out a sensible interpretation of the results, for chemical, biochemical or materials science applications. The review mainly focuses on X-ray diffraction techniques and refinement of experimental models, in particular multipolar models. Neutron diffraction, which was widely used in the past to fix accurate positions of atoms, is now used for more specific purposes. The review illustrates three principal analyses of the experimental or theoretical electron density, based on quantum chemical, semi-empirical or empirical interpretation schemes, such as the quantum theory of atoms in molecules, the semiclassical evaluation of interaction energies and the Hirshfeld analysis. In particular, it is shown that a simple topological analysis based on a partition of the electron density cannot alone reveal the whole nature of chemical bonding. More information based on the pair density is necessary. A connection between quantum mechanics and observable quantities is given in order to provide the physical grounds to explain the observations and to justify the interpretations.