http://journals.iucr.org/a/issues/2009/03/00/isscontsbdy.html Acta Crystallographica Section A: Foundations of Crystallography publishes papers reporting fundamental advances in all areas of crystallography in the broadest sense. The central themes are, on the one hand, experimental and theoretical studies of the properties and arrangements of atoms, ions and molecules in condensed matter, ideal or real, and of their symmetry and, on the other, the theoretical and experimental aspects of the various methods to determine these arrangements. en Copyright (c) 2009 International Union of Crystallography 2009-05-01 International Union of Crystallography International Union of Crystallography http://journals.iucr.org urn:issn:0108-7673 Acta Crystallographica Section A: Foundations of Crystallography publishes papers reporting fundamental advances in all areas of crystallography in the broadest sense. The central themes are, on the one hand, experimental and theoretical studies of the properties and arrangements of atoms, ions and molecules in condensed matter, ideal or real, and of their symmetry and, on the other, the theoretical and experimental aspects of the various methods to determine these arrangements. text/html Acta Crystallographica Section A: Foundations of Crystallography, Volume 65, Part 3, 2009 text yearly 6 2002-01-01T00:00+00:00 3 65 2009-05-01 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography 167 urn:issn:0108-7673 med@iucr.org May 2009 2009-05-01 http://journals.iucr.org/logos/rss10a.gif http://journals.iucr.org/a/issues/2009/03/00/isscontsbdy.html Still image http://scripts.iucr.org/cgi-bin/paper?sh5087 In the 60 years since its birth in 1948, the number of journals published by the International Union of Crystallography has risen from one to eight. A brief account of the history of the forerunner of the IUCr journals, Zeitschrift für Kristallographie, is given. The context of the birth of the IUCr and the first of its journals, Acta Crystallographica, is recalled. The circumstances which led to the growth of Acta into several sections, at first A and B then, successively, C, D, E and F, and the launch of two new journals, the Journal of Applied Crystallography and the Journal of Synchrotron Radiation, are described. The transition from print-on-paper to electronic journals is also remembered. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Authier, A. 2009-04-02 doi:10.1107/S0108767309007235 International Union of Crystallography The birth and growth of the publications and journals of the International Union of Crystallography from 1948 to 2008 are described. Details are given of the pre-war history that led up to their creation and development. en publishing Acta Crystallographica Journal of Applied Crystallography Journal of Synchrotron Radiation International Tables for Crystallography International Union of Crystallography In the 60 years since its birth in 1948, the number of journals published by the International Union of Crystallography has risen from one to eight. A brief account of the history of the forerunner of the IUCr journals, Zeitschrift für Kristallographie, is given. The context of the birth of the IUCr and the first of its journals, Acta Crystallographica, is recalled. The circumstances which led to the growth of Acta into several sections, at first A and B then, successively, C, D, E and F, and the launch of two new journals, the Journal of Applied Crystallography and the Journal of Synchrotron Radiation, are described. The transition from print-on-paper to electronic journals is also remembered. text/html 60 years of IUCr journals text 3 65 2009-04-02 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography feature articles 167 182 http://scripts.iucr.org/cgi-bin/paper?sh5083 Fourier syntheses are always affected by series-termination errors, which generate sets of positive and negative ripples around each main peak in the map. The interaction among the ripples distorts the profile of the map and moves peaks away from their correct positions. In a previous paper [Altomare et al. (2008). Acta Cryst. A64, 326–336] an algorithm was described which reduces the resolution bias by removing the effects of the ripples in direct space. In this paper the correction is performed in reciprocal space: the effect of the ripples on the atomic scattering factors is calculated and subtracted from the usual atomic scattering factors. The modified scattering factors are used to calculate new structure factors, from which more accurate electron-density maps may be obtained. The experimental tests show that the procedure minimizes the effects of the resolution bias and provides atomic positions that are more accurate than those provided by traditional approaches. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Altomare, A. Cuocci, C. Giacovazzo, C. Maggi, S. Moliterni, A. Rizzi, R. 2009-03-13 doi:10.1107/S0108767309003687 International Union of Crystallography Atomic scattering factors are modified to correct the resolution bias in electron-density maps. en electron-density maps resolution series-termination errors bias Fourier syntheses are always affected by series-termination errors, which generate sets of positive and negative ripples around each main peak in the map. The interaction among the ripples distorts the profile of the map and moves peaks away from their correct positions. In a previous paper [Altomare et al. (2008). Acta Cryst. A64, 326–336] an algorithm was described which reduces the resolution bias by removing the effects of the ripples in direct space. In this paper the correction is performed in reciprocal space: the effect of the ripples on the atomic scattering factors is calculated and subtracted from the usual atomic scattering factors. The modified scattering factors are used to calculate new structure factors, from which more accurate electron-density maps may be obtained. The experimental tests show that the procedure minimizes the effects of the resolution bias and provides atomic positions that are more accurate than those provided by traditional approaches. text/html Correcting electron-density resolution bias in reciprocal space text 3 65 2009-03-13 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 183 189 http://scripts.iucr.org/cgi-bin/paper?zm5053 A model-free method of reconstructing depth-specific lateral scattering from incident-angle-resolved grazing-incidence small-angle X-ray scattering (GISAXS) data is proposed. The information on the material which is available through variation of the X-ray penetration depth with incident angle is accessed through reference to the reflected branch of the GISAXS process. Reconstruction of the scattering from lateral density fluctuations is achieved by solving the resulting Fredholm integral equation with minimal a priori information about the experimental system. Results from simulated data generated for hypothetical multilayer polymer systems with constant absorption coefficient are used to verify that the method can be applied to cases with large X-ray penetration depths, as typically seen with polymer materials. Experimental tests on a spin-coated thick film of a blend of diblock copolymers demonstrate that the approach is capable of reconstruction of the scattering from a multilayer structure with the identification of lateral scattering profiles as a function of sample depth. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Singh, M.A. Groves, M.N. 2009-04-02 doi:10.1107/S0108767309007508 International Union of Crystallography A procedure for obtaining depth-specific scattering profiles of laterally defined nanostructure using grazing-incidence small-angle X-ray scattering is described. en depth profiling grazing-incidence small-angle X-ray scattering block copolymers A model-free method of reconstructing depth-specific lateral scattering from incident-angle-resolved grazing-incidence small-angle X-ray scattering (GISAXS) data is proposed. The information on the material which is available through variation of the X-ray penetration depth with incident angle is accessed through reference to the reflected branch of the GISAXS process. Reconstruction of the scattering from lateral density fluctuations is achieved by solving the resulting Fredholm integral equation with minimal a priori information about the experimental system. Results from simulated data generated for hypothetical multilayer polymer systems with constant absorption coefficient are used to verify that the method can be applied to cases with large X-ray penetration depths, as typically seen with polymer materials. Experimental tests on a spin-coated thick film of a blend of diblock copolymers demonstrate that the approach is capable of reconstruction of the scattering from a multilayer structure with the identification of lateral scattering profiles as a function of sample depth. text/html Depth profiling of polymer films with grazing-incidence small-angle X-ray scattering text 3 65 2009-04-02 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 190 201 http://scripts.iucr.org/cgi-bin/paper?eo5002 The TOPOS program package was used to generate all subnets of 3- to 12-coordinated binodal nets taken from the Reticular Chemistry Structure Resource database. 38 304 binodal nets with novel topologies were revealed and stored in the TTD collection. A new invariant, the adjacency matrix of the shell graph of a node, is proposed to distinguish the node local topology. With this invariant, the first six examples of binodal-quasi-uninodal nets were discovered. 4604 organic and metal-organic frameworks were analyzed to find examples of the topologies generated. It was shown that many edge-transitive nets as well as unknown topologies occur in crystal structures. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Blatov, V.A. Proserpio, D.M. 2009-04-02 doi:10.1107/S0108767309006096 International Union of Crystallography The TOPOS program package was used to generate all subnets of 3- to 12-coordinated binodal nets taken from the Reticular Chemistry Structure Resource database. 38 304 binodal nets with novel topologies were revealed and stored in the TTD collection. en topological relations three-periodic nets binodal nets edge-transitive nets The TOPOS program package was used to generate all subnets of 3- to 12-coordinated binodal nets taken from the Reticular Chemistry Structure Resource database. 38 304 binodal nets with novel topologies were revealed and stored in the TTD collection. A new invariant, the adjacency matrix of the shell graph of a node, is proposed to distinguish the node local topology. With this invariant, the first six examples of binodal-quasi-uninodal nets were discovered. 4604 organic and metal-organic frameworks were analyzed to find examples of the topologies generated. It was shown that many edge-transitive nets as well as unknown topologies occur in crystal structures. text/html Topological relations between three-periodic nets. II. Binodal nets text 3 65 2009-04-02 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 202 212 http://scripts.iucr.org/cgi-bin/paper?eo5001 The link between the crystal topology and symmetry is examined, focusing on the conditions under which a structure with a given topology can exhibit a certain symmetry. By defining embeddings for quotient graphs (finite representations of crystal topologies) and the corresponding nets (the graph-theoretical equivalents of structures), a strong relationship between the automorphisms of the quotient graphs and the symmetry of the embedded net is established. This allows one to constrain the relative node positions under the premise that an embedding of a net has a certain symmetry, and allows one to assign nodes to equivalents of Wyckoff positions. Two-dimensional examples as well as known crystal structures are used to illustrate the findings. A comparison with a related publication and a discussion on whether constraints on distances between atoms and on bond angles result in restrictions on symmetry without causing confusion conclude the work. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Thimm, G. 2009-03-13 doi:10.1107/S0108767309003638 International Union of Crystallography On the basis of a link between a graph-theoretical description of crystal structures and their symmetries, atom positions are constrained. Examples show the presence of implicit and forbidden symmetries. en crystal topologies quotient graphs nets symmetry The link between the crystal topology and symmetry is examined, focusing on the conditions under which a structure with a given topology can exhibit a certain symmetry. By defining embeddings for quotient graphs (finite representations of crystal topologies) and the corresponding nets (the graph-theoretical equivalents of structures), a strong relationship between the automorphisms of the quotient graphs and the symmetry of the embedded net is established. This allows one to constrain the relative node positions under the premise that an embedding of a net has a certain symmetry, and allows one to assign nodes to equivalents of Wyckoff positions. Two-dimensional examples as well as known crystal structures are used to illustrate the findings. A comparison with a related publication and a discussion on whether constraints on distances between atoms and on bond angles result in restrictions on symmetry without causing confusion conclude the work. text/html Crystal topologies – the achievable and inevitable symmetries text 3 65 2009-03-13 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 213 226 http://scripts.iucr.org/cgi-bin/paper?tn5012 We computed Debye–Waller factors in the temperature range from 0.1 to 1000 K for AlN, GaN, InN, ZnO and CdO with the wurtzite-type structure. The Debye–Waller factors were derived from phonon densities of states obtained from Hellmann–Feynman forces computed within the density-functional-theory formalism. The temperature dependences of the Debye–Waller factors were fitted and fit parameters are given. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Schowalter, M. Rosenauer, A. Titantah, J.T. Lamoen, D. 2009-03-13 doi:10.1107/S0108767309004966 International Union of Crystallography The Debye–Waller factors of wurtzite-type semiconductors are calculated from ab initio force constants and fitted in the temperature range from 0.1 to 1000 K. en Debye–Waller factors semiconductors density functional theory wurtzite-type structures We computed Debye–Waller factors in the temperature range from 0.1 to 1000 K for AlN, GaN, InN, ZnO and CdO with the wurtzite-type structure. The Debye–Waller factors were derived from phonon densities of states obtained from Hellmann–Feynman forces computed within the density-functional-theory formalism. The temperature dependences of the Debye–Waller factors were fitted and fit parameters are given. text/html Temperature-dependent Debye–Waller factors for semiconductors with the wurtzite-type structure text 3 65 2009-03-13 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 227 231 http://scripts.iucr.org/cgi-bin/paper?cn5017 The relationship between the equations used in the atomic pair distribution function (PDF) method and those commonly used in small-angle-scattering (SAS) analyses is explicitly shown. The origin of the sloping baseline, −4πrρ0, in PDFs of bulk materials is identified as originating from the SAS intensity that is neglected in PDF measurements. The nonlinear baseline in nanoparticles has the same origin, and contains information about the shape and size of the nanoparticles. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Farrow, C.L. Billinge, S.J.L. 2009-04-02 doi:10.1107/S0108767309009714 International Union of Crystallography The exact relationship between the atomic pair distribution function and small-angle-scattering equations is established and discussed. This has implications for the structural modeling of nanoparticles. en atomic pair distribution function small-angle scattering nanoparticles modeling The relationship between the equations used in the atomic pair distribution function (PDF) method and those commonly used in small-angle-scattering (SAS) analyses is explicitly shown. The origin of the sloping baseline, −4πrρ0, in PDFs of bulk materials is identified as originating from the SAS intensity that is neglected in PDF measurements. The nonlinear baseline in nanoparticles has the same origin, and contains information about the shape and size of the nanoparticles. text/html Relationship between the atomic pair distribution function and small-angle scattering: implications for modeling of nanoparticles text 3 65 2009-04-02 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 232 239 http://scripts.iucr.org/cgi-bin/paper?sh5082 The discrete tomography of mathematical quasicrystals with icosahedral symmetry is investigated, placing emphasis on reconstruction and uniqueness problems. The work is motivated by the requirement in materials science for the unique reconstruction of the structures of icosahedral quasicrystals from a small number of images produced by quantitative high-resolution transmission electron microscopy. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Huck, C. 2009-03-13 doi:10.1107/S0108767309004292 International Union of Crystallography The main problems in the discrete tomography of mathematical quasicrystals with icosahedral symmetry are investigated. en icosahedral quasicrystals discrete tomography icosahedral symmetry high-resolution transmission electron microscopy The discrete tomography of mathematical quasicrystals with icosahedral symmetry is investigated, placing emphasis on reconstruction and uniqueness problems. The work is motivated by the requirement in materials science for the unique reconstruction of the structures of icosahedral quasicrystals from a small number of images produced by quantitative high-resolution transmission electron microscopy. text/html Discrete tomography of icosahedral model sets text 3 65 2009-03-13 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 240 248 http://scripts.iucr.org/cgi-bin/paper?pz5061 The full symmetry groups of carbon nanotori are investigated. It is shown that that the symmetry group of a chiral (n1, n2) nanotorus is isomorphic to D2mq/n, where m and q are the number of lattice points on the torus circumference vector and the number of graphene hexagons in the nanotorus unit cell, respectively, and n = gcd(n1, n2). It is also shown that the symmetry group of zigzag and armchair (achiral) nanotori is D_{4m} \times {\bb Z}_{2}, where D2k and {\bb Z}_{k} are the dihedral group of order 2k and the cyclic group of order k, respectively. The irreducible representations and characters of these groups are discussed. Copyright (c) 2009 International Union of Crystallography urn:issn:0108-7673 Arezoomand, M. Taeri, B. 2009-04-02 doi:10.1107/S0108767309008228 International Union of Crystallography The full symmetry groups of carbon nanotori are investigated and the irreducible representations and characters of the symmetry groups of chiral and achiral nanotori are discussed. en full symmetry group carbon nanotorus representation theory The full symmetry groups of carbon nanotori are investigated. It is shown that that the symmetry group of a chiral (n1, n2) nanotorus is isomorphic to D2mq/n, where m and q are the number of lattice points on the torus circumference vector and the number of graphene hexagons in the nanotorus unit cell, respectively, and n = gcd(n1, n2). It is also shown that the symmetry group of zigzag and armchair (achiral) nanotori is D_{4m} \times {\bb Z}_{2}, where D2k and {\bb Z}_{k} are the dihedral group of order 2k and the cyclic group of order k, respectively. The irreducible representations and characters of these groups are discussed. text/html The full symmetry and irreducible representations of nanotori text 3 65 2009-04-02 Copyright (c) 2009 International Union of Crystallography Acta Crystallographica Section A: Foundations of Crystallography research papers 249 252