title: Modelling the experimental electron density: only the synergy of various approaches can tackle the new challenges.
abstract: Electron density is a fundamental quantity that enables understanding of the chemical bonding in a molecule or in a solid and the chemical/physical property of a material. Because electrons have a charge and a spin, two kinds of electron densities are available. Moreover, because electron distribution can be described in momentum or in position space, charge and spin density have two definitions and they can be observed through Bragg (for the position space) or Compton (for the momentum space) diffraction experiments, using X-rays (charge density) or polarized neutrons (spin density). In recent years, we have witnessed many advances in this field, stimulated by the increased power of experimental techniques. However, an accurate modelling is still necessary to determine the desired functions from the acquired data. The improved accuracy of measurements and the possibility to combine information from different experimental techniques require even more flexibility of the models. In this short review, we analyse some of the most important topics that have emerged in the recent literature, especially the most thought-provoking at the recent IUCr general meeting in Montreal.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Piero
authors.initials: P
authors.lastname: Macchi
authors.affiliation: Laboratoire Structures Propriétés et Modélisation des Solides, UMR 8580, Université Paris Saclay CentraleSupélec, CNRS, Grande Voie des Vignes, 92295 Chatenay-Malabry, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Gillet
authors.affiliation: Institut Lavoisier de Versailles, Université de Versailles Saint Quentin en Yvelines , 45 Avenue des Etats-Unis, Versailles, 78035, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Taulelle
authors.affiliation: Materials Science Institute of Aragón, CSIC-University of Zaragoza , Zaragoza, 50009, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Campo
authors.affiliation: Cristallographie, Résonance Magnetique et Modélisations, CRM2, UMR 7036, Institut Jean Barriol, Université de Lorraine , Vandoeuvre-les-Nancy, BP239, F54506, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Claiser
authors.affiliation: Cristallographie, Résonance Magnetique et Modélisations, CRM2, UMR 7036, Institut Jean Barriol, Université de Lorraine , Vandoeuvre-les-Nancy, BP239, F54506, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Lecomte
keywords: charge density; momentum density; spin density