Forthcoming article in Acta Crystallographica Section A Foundations and Advances
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Acta Crystallographica Section A: Foundations and Advances 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-gbCopyright (c) 2019 International Union of CrystallographyInternational Union of CrystallographyInternational Union of Crystallographyhttps://journals.iucr.orgurn:issn:0108-7673Acta Crystallographica Section A: Foundations and Advances 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/htmlActa Crystallographica Section A Foundations and Advancestextdaily12002-01-01T00:00+00:00med@iucr.orgActa Crystallographica Section A Foundations and AdvancesCopyright (c) 2019 International Union of Crystallographyurn:issn:0108-7673Forthcoming article in Acta Crystallographica Section A Foundations and Advanceshttp://journals.iucr.org/logos/rss10a.gif
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Still imageA parameter-free double-shear theory for lath martensite
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In analogy to the original phenomenological theory of martensite crystallography, a double-shear theory for lath martensite is proposed which chooses the shearing systems as those that are macroscopically equivalent to double twinning. Using only the additional assumptions of overall small shape strain magnitude and a condition of maximal compatibility, this approach naturally gives rise to {5 5 7}γ habit planes and orientation relationships close to the Kurdjumov–Sachs model.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Koumatos and Muehlemanndoi:10.1107/S205327331901252XInternational Union of CrystallographyIn analogy to the original phenomenological theory of martensite crystallography, a double-shear theory for lath martensite is proposed which chooses the shearing systems as those that are macroscopically equivalent to double twinning. Using only the additional assumptions of overall small shape strain magnitude and a condition of maximal compatibility, this approach naturally gives rise to {5 5 7}γ habit planes and orientation relationships close to the Kurdjumov–Sachs model.enLATH MARTENSITE; DOUBLE SHEAR; 557 HABIT PLANES; ORIENTATION RELATIONSHIPS; F.C.C. TO B.C.C.; LOW-CARBON STEEL; KURDJUMOV-SACHS; NISHIYAMA-WASSERMANNIn analogy to the original phenomenological theory of martensite crystallography, a double-shear theory for lath martensite is proposed which chooses the shearing systems as those that are macroscopically equivalent to double twinning. Using only the additional assumptions of overall small shape strain magnitude and a condition of maximal compatibility, this approach naturally gives rise to {5 5 7}γ habit planes and orientation relationships close to the Kurdjumov–Sachs model.text/htmlA parameter-free double-shear theory for lath martensitetextRelativistic correction of atomic scattering factors for high-energy electron diffraction
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Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Markus Lentzendoi:10.1107/S2053273319012191International Union of CrystallographyRelativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.enELECTRON DIFFRACTION; ATOMIC SCATTERING FACTORS; RELATIVITY THEORY; SCHRODINGER EQUATIONRelativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.text/htmlRelativistic correction of atomic scattering factors for high-energy electron diffractiontextNormally supportive sublattices of crystallographic space groups
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Subgroups of 3D crystallographic space groups that are also normal subgroups of 3D space groups have long been of interest. For each arithmetic crystal class of 3D space groups, the sublattices capable of supporting such subgroups are tabulated.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Miles A. Clemens et al.doi:10.1107/S205327331901218XInternational Union of CrystallographySubgroups of 3D crystallographic space groups that are also normal subgroups of 3D space groups have long been of interest. For each arithmetic crystal class of 3D space groups, the sublattices capable of supporting such subgroups are tabulated.enSPACE-GROUP SYMMETRY; NORMAL SUBGROUP; CRYSTALLOGRAPHIC SUBLATTICESubgroups of 3D crystallographic space groups that are also normal subgroups of 3D space groups have long been of interest. For each arithmetic crystal class of 3D space groups, the sublattices capable of supporting such subgroups are tabulated.text/htmlNormally supportive sublattices of crystallographic space groupstextX-ray interference fringes from a weakly bent plane-parallel crystal with negative strain gradient
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In the waves emitted from the entrance, back and lateral surfaces of a very weakly bent plane-parallel perfect crystal with negative strain gradient, X-ray interference fringes between two refracted beams with different hyperbolic trajectories were observed when the strain was very weak, of the order of 10−7.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Tomoe Fukamachi et al.doi:10.1107/S2053273319011859International Union of CrystallographyIn the waves emitted from the entrance, back and lateral surfaces of a very weakly bent plane-parallel perfect crystal with negative strain gradient, X-ray interference fringes between two refracted beams with different hyperbolic trajectories were observed when the strain was very weak, of the order of 10−7.enINTERFERENCE FRINGES; MIRAGE FRINGES; X-RAY BEAM TRAJECTORY; BENT CRYSTAL; MULTIPLE BRAGG DIFFRACTION; DYNAMICAL THEORY OF X-RAY DIFFRACTIONIn the waves emitted from the entrance, back and lateral surfaces of a very weakly bent plane-parallel perfect crystal with negative strain gradient, X-ray interference fringes between two refracted beams with different hyperbolic trajectories were observed when the strain was very weak, of the order of 10−7.text/htmlX-ray interference fringes from a weakly bent plane-parallel crystal with negative strain gradienttextMeasurement and alleviation of subsurface damage in a thick-crystal neutron interferometer
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The alleviation of subsurface machining damage in a thick-crystal neutron interferometer is investigated by testing the interferometer throughout an annealing and chemical etching post-fabrication process. Spatially varying Bragg-plane angular misalignments between diffracting components of the interferometer are lessened from 10−5 rad to less than 10−9 rad.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733B. Heacock et al.doi:10.1107/S2053273319011604International Union of CrystallographyThe alleviation of subsurface machining damage in a thick-crystal neutron interferometer is investigated by testing the interferometer throughout an annealing and chemical etching post-fabrication process. Spatially varying Bragg-plane angular misalignments between diffracting components of the interferometer are lessened from 10−5 rad to less than 10−9 rad.enSILICON; INTERFEROMETERS; NEUTRONS; MACHINING; ANNEALINGThe alleviation of subsurface machining damage in a thick-crystal neutron interferometer is investigated by testing the interferometer throughout an annealing and chemical etching post-fabrication process. Spatially varying Bragg-plane angular misalignments between diffracting components of the interferometer are lessened from 10−5 rad to less than 10−9 rad.text/htmlMeasurement and alleviation of subsurface damage in a thick-crystal neutron interferometertextA universal algorithm for finding the shortest distance between systems of points
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A universal and effective algorithm is proposed for geometrical comparison of abstract sets of n points in Euclidean space. Applications of the algorithm for comparison of both finite (ligands) and periodic (nets) chemical objects are considered.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Igor A. Blatov et al.doi:10.1107/S2053273319011628International Union of CrystallographyA universal and effective algorithm is proposed for geometrical comparison of abstract sets of n points in Euclidean space. Applications of the algorithm for comparison of both finite (ligands) and periodic (nets) chemical objects are considered.enSYSTEMS OF POINTS; SHORTEST DISTANCE; ALGORITHMSA universal and effective algorithm is proposed for geometrical comparison of abstract sets of n points in Euclidean space. Applications of the algorithm for comparison of both finite (ligands) and periodic (nets) chemical objects are considered.text/htmlA universal algorithm for finding the shortest distance between systems of pointstextPerfect colorings of patterns with multiple orbits
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Perfect colorings of patterns with multiple orbits were characterized, with a focus on colorings where the orbits share colors. These results were then applied to construct perfect and non-perfect colorings of various symmetrical objects.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Junio and Walodoi:10.1107/S2053273319011562International Union of CrystallographyPerfect colorings of patterns with multiple orbits were characterized, with a focus on colorings where the orbits share colors. These results were then applied to construct perfect and non-perfect colorings of various symmetrical objects.enPERFECT COLORINGS; MULTIPLE ORBITS; COLOR SHARINGPerfect colorings of patterns with multiple orbits were characterized, with a focus on colorings where the orbits share colors. These results were then applied to construct perfect and non-perfect colorings of various symmetrical objects.text/htmlPerfect colorings of patterns with multiple orbitstextCrystallography of three-dimensional fluid flows with chirality in hexagonal cases
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Magnetic groups are applied to three-dimensional fluid flows with chirality, which are called Beltrami flows. Eight Beltrami flows are derived and studied using Wyckoff positions. The crystal-like structures of their tube-like surfaces called invariant tori are numerically observed.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Takahiro Nishiyamadoi:10.1107/S205327331901146XInternational Union of CrystallographyMagnetic groups are applied to three-dimensional fluid flows with chirality, which are called Beltrami flows. Eight Beltrami flows are derived and studied using Wyckoff positions. The crystal-like structures of their tube-like surfaces called invariant tori are numerically observed.enMAGNETIC GROUPS; CHIRALITY; HEXAGONAL SYMMETRY; BELTRAMI FLOW; INVARIANT TORUSMagnetic groups are applied to three-dimensional fluid flows with chirality, which are called Beltrami flows. Eight Beltrami flows are derived and studied using Wyckoff positions. The crystal-like structures of their tube-like surfaces called invariant tori are numerically observed.text/htmlCrystallography of three-dimensional fluid flows with chirality in hexagonal casestextBayesian machine learning improves single-wavelength anomalous diffraction phasing
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In this paper the a posteriori probability densities of anomalous structure factor amplitude differences were estimated by the Markov Chain Monte Carlo machine learning method. The model incorporated the correlation between the different Bijvoet pairs and the improved estimates were shown to be beneficial for SAD phasing.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Garcia-Bonete and Katonadoi:10.1107/S2053273319011446International Union of CrystallographyIn this paper the a posteriori probability densities of anomalous structure factor amplitude differences were estimated by the Markov Chain Monte Carlo machine learning method. The model incorporated the correlation between the different Bijvoet pairs and the improved estimates were shown to be beneficial for SAD phasing.enSINGLE-WAVELENGTH X-RAY ANOMALOUS DIFFRACTION; FRIEDEL'S AND BIJVOET'S PAIRS; CONTINUOUS AND INVERSE-BEAM GEOMETRY COLLECTION; BAYESIAN INFERENCE; SURVIVINIn this paper the a posteriori probability densities of anomalous structure factor amplitude differences were estimated by the Markov Chain Monte Carlo machine learning method. The model incorporated the correlation between the different Bijvoet pairs and the improved estimates were shown to be beneficial for SAD phasing.text/htmlBayesian machine learning improves single-wavelength anomalous diffraction phasingtextX-ray constrained spin-coupled technique: theoretical details and further assessment of the method
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A new method that extends the Jayatilaka X-ray constrained wavefunction approach in the framework of the spin-coupled technique of the valence bond theory is presented. The proposed strategy enables the extraction of traditional chemical information (e.g. weights of resonance structures) from experimental X-ray diffraction data without imposing constraints a priori or performing further analyses a posteriori.Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Alessandro Genoni et al.doi:10.1107/S2053273319011021International Union of CrystallographyA new method that extends the Jayatilaka X-ray constrained wavefunction approach in the framework of the spin-coupled technique of the valence bond theory is presented. The proposed strategy enables the extraction of traditional chemical information (e.g. weights of resonance structures) from experimental X-ray diffraction data without imposing constraints a priori or performing further analyses a posteriori.enX-RAY CONSTRAINED WAVEFUNCTION; QUANTUM CRYSTALLOGRAPHY; VALENCE BOND THEORY; SPIN-COUPLED METHODA new method that extends the Jayatilaka X-ray constrained wavefunction approach in the framework of the spin-coupled technique of the valence bond theory is presented. The proposed strategy enables the extraction of traditional chemical information (e.g. weights of resonance structures) from experimental X-ray diffraction data without imposing constraints a priori or performing further analyses a posteriori.text/htmlX-ray constrained spin-coupled technique: theoretical details and further assessment of the methodtextBerry Phases in Electronic Structure Theory. Electric Polarization, Orbital Magnetization and Topological Insulators. By David Vanderbilt. Cambridge University Press, 2018. Hardback, pp. x+384. Price GBP 59.99. ISBN 9781107157651.
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Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Laurent Chaputdoi:10.1107/S2053273319009744International Union of CrystallographyenBOOK REVIEW; BERRY PHASES; ELECTRONIC STRUCTURE; TOPOLOGICAL INSULATORStext/htmlBerry Phases in Electronic Structure Theory. Electric Polarization, Orbital Magnetization and Topological Insulators. By David Vanderbilt. Cambridge University Press, 2018. Hardback, pp. x+384. Price GBP 59.99. ISBN 9781107157651.textA Journey into Reciprocal Space: A Crystallographer's Perspective. By A. M. Glazer. Morgan & Claypool, 2017. Paperback, pp. 190. Price USD 55.00. ISBN 9781681746203.
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Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Berthold Stögerdoi:10.1107/S2053273319006983International Union of CrystallographyenBOOK REVIEW; RECIPROCAL SPACEtext/htmlA Journey into Reciprocal Space: A Crystallographer's Perspective. By A. M. Glazer. Morgan & Claypool, 2017. Paperback, pp. 190. Price USD 55.00. ISBN 9781681746203.textIslamic Geometric Patterns: Their Historical Development and Traditional Methods of Construction with a chapter on the use of computer algorithms to generate Islamic geometric patterns by Craig Kaplan. By Jay Bonner. Springer, 2017. Pp. XXV+525. Price USD 139.00. ISBN 978-1-4939-7921-9 (softcover) 978-1-4419-0216-0 (hardcover). ISBN 978-1-4419-0216-0.
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Copyright (c) 2019 International Union of Crystallographyurn:issn:2053-2733Greg McColmdoi:International Union of CrystallographyenBOOK REVIEW; ISLAMIC GEOMETRIC PATTERNStext/htmlIslamic Geometric Patterns: Their Historical Development and Traditional Methods of Construction with a chapter on the use of computer algorithms to generate Islamic geometric patterns by Craig Kaplan. By Jay Bonner. Springer, 2017. Pp. XXV+525. Price USD 139.00. ISBN 978-1-4939-7921-9 (softcover) 978-1-4419-0216-0 (hardcover). ISBN 978-1-4419-0216-0.text