title: Experimental determination of core electron deformation in diamond.
abstract: Synchrotron powder X-ray diffraction data are used to determine the core electron deformation of diamond. Core shell contraction inherently linked to covalent bond formation is observed in close correspondence with theoretical predictions. Accordingly, a precise and physically sound reconstruction of the electron density in diamond necessitates the use of an extended multipolar model, which abandons the assumption of an inert core. The present investigation is facilitated by negligible model bias in the extraction of structure factors, which is accomplished by simultaneous multipolar and Rietveld refinement accurately determining an atomic displacement parameter (ADP) of 0.00181 (1) Å(2). The deconvolution of thermal motion is a critical step in experimental core electron polarization studies, and for diamond it is imperative to exploit the monatomic crystal structure by implementing Wilson plots in determination of the ADP. This empowers the electron-density analysis to precisely administer both the deconvolution of thermal motion and the employment of the extended multipolar model on an experimental basis.
authors.affiliation: Center for Materials Crystallography, Department of Chemistry and iNANO, Langelandsgade 140, Aarhus C 8000, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Bindzus
authors.affiliation: Niels Bohr Institute, Universitetsparken 5, Copenhagen 2100, Denmark.
authors.forename: Tine
authors.initials: T
authors.lastname: Straasø
authors.affiliation: Center for Materials Crystallography, Department of Chemistry and iNANO, Langelandsgade 140, Aarhus C 8000, Denmark.
authors.forename: Nanna
authors.initials: N
authors.lastname: Wahlberg
authors.affiliation: Center for Materials Crystallography, Department of Chemistry and iNANO, Langelandsgade 140, Aarhus C 8000, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Becker
authors.affiliation: Center for Materials Crystallography, Department of Chemistry and iNANO, Langelandsgade 140, Aarhus C 8000, Denmark.
authors.forename: Lasse
authors.initials: L
authors.lastname: Bjerg
authors.affiliation: Department of Inorganic Chemistry, Georg-August-Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Lock
authors.affiliation: PETRA III, DESY Photon Science, Notkestrasse 85, D-22607 Hamburg, Germany.
authors.forename: Ann Christin
authors.initials: AC
authors.lastname: Dippel
authors.affiliation: Center for Materials Crystallography, Department of Chemistry and iNANO, Langelandsgade 140, Aarhus C 8000, Denmark.
authors.forename: Bo B
authors.initials: BB
authors.lastname: Iversen
keywords: atomic displacement parameter; core polarization; electron density; extended multipolar model; structure-factor extraction; synchrotron powder X-ray diffraction