title: Synchrotron powder diffraction of silicon: high-quality structure factors and electron density.
abstract: Crystalline silicon is an ideal compound to test the current state of experimental structure factors and corresponding electron densities. High-quality structure factors have been measured on crystalline silicon with synchrotron powder X-ray diffraction. They are in excellent agreement with benchmark Pendellösung data having comparable accuracy and precision, but acquired in far less time and to a much higher resolution (sin θ/λ < 1.7 Å(-1)). The extended data range permits an experimental modelling of not only the valence electron density but also the core deformation in silicon, establishing an increase of the core density upon bond formation in crystalline silicon. Furthermore, a physically sound procedure for evaluating the standard deviation of powder-derived structure factors has been applied. Sampling statistics inherently account for contributions from photon counts as well as the limited number of diffracting particles, where especially the latter are particularly difficult to handle.
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Nanna
authors.initials: N
authors.lastname: Wahlberg
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Bindzus
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Lasse
authors.initials: L
authors.lastname: Bjerg
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Becker
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Ann Christin
authors.initials: AC
authors.lastname: Dippel
authors.affiliation: Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus 8000, Denmark.
authors.forename: Bo Brummerstedt
authors.initials: BB
authors.lastname: Iversen
keywords: charge density; core polarization; silicon; structure factors; synchrotron powder X-ray diffraction