http://journals.iucr.org/a/journalhomepage.html Acta Crystallographica Section A: Foundations of Crystallography covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered. en-gb Copyright (c) 2012 International Union of Crystallography International Union of Crystallography International Union of Crystallography http://journals.iucr.org urn:issn:0108-7673 Acta Crystallographica Section A: Foundations of Crystallography covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered. text/html Acta Crystallographica Section A Foundations of Crystallography text daily 1 2002-01-01T00:00+00:00 med@iucr.org Acta Crystallographica Section A Foundations of Crystallography Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 http://journals.iucr.org/logos/rss10a.gif http://journals.iucr.org/a/journalhomepage.html Still image http://journals.iucr.org/a/services/forthcoming.html#eo5016 A rigorous method is proposed to describe and classify topology of entanglements between periodic networks if the links are of Hopf type. The catenation pattern is unambiguously identified by so-called Hopf ring net that consists of barycenters of catenating rings with edges corresponding to the Hopf links. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 Eugeny V. Alexandrov et al. doi: International Union of Crystallography A rigorous method is proposed to describe and classify topology of entanglements between periodic networks if the links are of Hopf type. The catenation pattern is unambiguously identified by so-called Hopf ring net that consists of barycenters of catenating rings with edges corresponding to the Hopf links. en CRYSTAL NETWORKS; INTERPENETRATION; POLYCATENATION; SELF-CATENATION; HOPF RING NET A rigorous method is proposed to describe and classify topology of entanglements between periodic networks if the links are of Hopf type. The catenation pattern is unambiguously identified by so-called Hopf ring net that consists of barycenters of catenating rings with edges corresponding to the Hopf links. text/html A topological method for classification of entanglements in crystal networks text http://journals.iucr.org/a/services/forthcoming.html#eo5015 Phyllotaxis, how to get a homogeneous distribution of points confined inside a flat disk. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 J-F. Sadoc et al. doi: International Union of Crystallography Phyllotaxis, how to get a homogeneous distribution of points confined inside a flat disk. en ; ; ; Phyllotaxis, how to get a homogeneous distribution of points confined inside a flat disk. text/html Phyllotaxis: a non conventional crystalline solution to packing efficiency in situations with radial symmetry text http://journals.iucr.org/a/services/forthcoming.html#wx5017 Based on a self-consistent wave approximation for solving the integral wave equation, the grazing-incidence small-angle X-ray scattering from a random rough surface is considered to test the optical theorem feasibility. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 F. N. Chukhovskii doi: International Union of Crystallography Based on a self-consistent wave approximation for solving the integral wave equation, the grazing-incidence small-angle X-ray scattering from a random rough surface is considered to test the optical theorem feasibility. en PLEASE PROVIDE KEYWORDS; ; ; Based on a self-consistent wave approximation for solving the integral wave equation, the grazing-incidence small-angle X-ray scattering from a random rough surface is considered to test the optical theorem feasibility. text/html On the optical theorem feasibility using a self-consistent wave approximation model for the grazing-incidence small-angle X-ray scattering from rough surfaces text http://journals.iucr.org/a/services/forthcoming.html#pc5010 The multipolar electron distribution of the title compound was compared with a spherical-charge modelling of the atoms, bonding density and lone pairs. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 Noureddine Dadda et al. doi:10.1107/S0108767312016571 International Union of Crystallography The multipolar electron distribution of the title compound was compared with a spherical-charge modelling of the atoms, bonding density and lone pairs. en ATOMIC CHARGES; BONDING ELECTRON DENSITY; LONE PAIRS The multipolar electron distribution of the title compound was compared with a spherical-charge modelling of the atoms, bonding density and lone pairs. text/html Charge-density analysis and electrostatic properties of 2-carboxy-4-methylanilinium chloride mono­hydrate obtained using a multipolar and a spherical-charges model text http://journals.iucr.org/a/services/forthcoming.html#pf0097 Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 doi:10.1107/S0108767312016534 International Union of Crystallography en BOOK RECEIVED text/html Structure of Materials. An Introduction to Crystallography, Diffraction and Symmetry. By Marc De Graef and Michael E. McHenry. Pp. xxxi+844. Cambridge: Cambridge University Press. 3rd printing, 2010. Price (hardback) USD 118.00. ISBN: 978-0521651516. text http://journals.iucr.org/a/services/forthcoming.html#pc5009 An algorithm for the calculation of the variance of electron-density maps via fast Fourier transform is proposed. A study of the related features is described. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 Giacovazzo and Mazzone doi:10.1107/S0108767312015772 International Union of Crystallography An algorithm for the calculation of the variance of electron-density maps via fast Fourier transform is proposed. A study of the related features is described. en VARIANCE; ELECTRON-DENSITY MAPS; STRUCTURE ANALYSIS An algorithm for the calculation of the variance of electron-density maps via fast Fourier transform is proposed. A study of the related features is described. text/html A practical study of the electron-density-map variance text http://journals.iucr.org/a/services/forthcoming.html#td5006 The interaction of a scalar wave with a single Si crystal is treated using Ewald's self-consistent field method. The reflectivities of allowed and forbidden reflections in the Bragg geometry valid for both coplanar and non-coplanar cases are derived. It is shown that there exists a very narrow reflectivity peak of the forbidden reflection. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 P. Dub and O. Litzman doi:10.1107/S0108767312014705 International Union of Crystallography The interaction of a scalar wave with a single Si crystal is treated using Ewald's self-consistent field method. The reflectivities of allowed and forbidden reflections in the Bragg geometry valid for both coplanar and non-coplanar cases are derived. It is shown that there exists a very narrow reflectivity peak of the forbidden reflection. en DYNAMICAL DIFFRACTION THEORY; FORBIDDEN REFLECTIONS The interaction of a scalar wave with a single Si crystal is treated using Ewald's self-consistent field method. The reflectivities of allowed and forbidden reflections in the Bragg geometry valid for both coplanar and non-coplanar cases are derived. It is shown that there exists a very narrow reflectivity peak of the forbidden reflection. text/html Multiple wave scattering on a bordered crystal. Translation symmetry breaking and forbidden reflections text http://journals.iucr.org/a/services/forthcoming.html#pc5011 An extension is proposed to the rigid-bond description of atomic thermal motion in crystals. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 Andrea Thorn et al. doi:10.1107/S0108767312014535 International Union of Crystallography An extension is proposed to the rigid-bond description of atomic thermal motion in crystals. en RIGID-BOND TEST; REFINEMENT RESTRAINTS; ANISOTROPIC DISPLACEMENT PARAMETERS An extension is proposed to the rigid-bond description of atomic thermal motion in crystals. text/html Enhanced rigid-bond restraints text http://journals.iucr.org/a/services/forthcoming.html#wl5158 The propagation of electron vortices in crystals is studied numerically. It is found that angular momentum is exchanged between the probe beam and the crystal lattice. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 Löffler and Schattschneider doi:10.1107/S0108767312013189 International Union of Crystallography The propagation of electron vortices in crystals is studied numerically. It is found that angular momentum is exchanged between the probe beam and the crystal lattice. en TOPOLOGICAL CHARGE; ELECTRON VORTEX; DYNAMIC DIFFRACTION The propagation of electron vortices in crystals is studied numerically. It is found that angular momentum is exchanged between the probe beam and the crystal lattice. text/html Elastic propagation of fast electron vortices through crystals text http://journals.iucr.org/a/services/forthcoming.html#wl5156 Crystal-field effects in the non-standard amino acid l-homoserine were investigated. Benchmark results from periodic B3LYP calculations are well reproduced by point-charge models. Basis-set representations of the electron density show subtle features further away from the nuclei, which cannot be retrieved by the Hansen/Coppens multipole model. Copyright (c) 2012 International Union of Crystallography urn:issn:0108-7673 B. Dittrich et al. doi:10.1107/S0108767312013001 International Union of Crystallography Crystal-field effects in the non-standard amino acid l-homoserine were investigated. Benchmark results from periodic B3LYP calculations are well reproduced by point-charge models. Basis-set representations of the electron density show subtle features further away from the nuclei, which cannot be retrieved by the Hansen/Coppens multipole model. en INTERACTION DENSITY; L-HOMOSERINE; HIRSHFELD-ATOM REFINEMENT; MULTIPOLE MODEL Crystal-field effects in the non-standard amino acid l-homoserine were investigated. Benchmark results from periodic B3LYP calculations are well reproduced by point-charge models. Basis-set representations of the electron density show subtle features further away from the nuclei, which cannot be retrieved by the Hansen/Coppens multipole model. text/html Crystal-field effects in l-homoserine: multipoles versus quantum chemistry text