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The development of powder profile refinement at the Reactor Centre Netherlands at Petten
10.1107/S2053273317018435 2018-03-01 With thousands of references to `Rietveld refinement' it is forgotten that the method did not suddenly appear in a flash of inspiration of a single person, but was the result of the work of three individuals working in the 1960s at the Reactor Centre Netherla... |
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Development of a joint refinement model for the spin‐resolved one‐electron reduced density matrix using different data sets
10.1107/S2053273318000384 2018-03-01 The paper describes a joint refinement model of the spin‐resolved one‐electron reduced density matrix using simultaneously magnetic structure factors and magnetic directional Compton profiles. The model is guided by two strategies: (i) variation of basis func... |
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Monoclinic sphere packings. II. Trivariant lattice complexes with mirror symmetry
10.1107/S2053273318000475 2018-03-01 All homogeneous sphere packings were derived that refer to the three trivariant monoclinic lattice complexes with mirror symmetry. In total, 29 types of sphere packings have been found. Only for three types is the maximal inherent symmetry of their sphere pac... |
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Phasing via pure crystallographic least squares: an unexpected feature
10.1107/S2053273318001407 2018-02-23 Crystallographic least‐squares techniques, the main tool for crystal structure refinement of small and medium‐size molecules, are for the first time used for ab initio phasing. It is shown that the chief obstacle to such use, the least‐squares severe converge... |
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Spatial displacement of forward‐diffracted X‐ray beams by perfect crystals
10.1107/S2053273318001419 2018-02-23 Time‐delayed, narrow‐band echoes generated by forward Bragg diffraction of an X‐ray pulse by a perfect thin crystal are exploited for self‐seeding at hard X‐ray free‐electron lasers. Theoretical predictions indicate that the retardation is strictly correlated... |
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Electron‐density critical points analysis and catastrophe theory to forecast structure instability in periodic solids
10.1107/S2053273317018381 2018-02-15 The critical points analysis of electron density, i.e. ρ(x), from ab initio calculations is used in combination with the catastrophe theory to show a correlation between ρ(x) topology and the appearance of instability that may lead to transformations of cryst... |
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Ab initio structure determination and quantitative disorder analysis on nanoparticles by electron diffraction tomography
10.1107/S2053273317018277 2018-02-15 Nanoscaled porous materials such as zeolites have attracted substantial attention in industry due to their catalytic activity, and their performance in sorption and separation processes. In order to understand the properties of such materials, current researc... |
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Coordination numbers of the vertex graph of a Penrose tiling
10.1107/S2053273318000062 2018-02-15 A new approach to study coordination shells and coordination sequences of quasiperiodic graphs is suggested. The structure of the coordination shells in the vertex graph of a Penrose tiling is described. An asymptotic formula for its coordination numbers is o... |
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A one-step mechanism for new twinning modes in magnesium and titanium alloys modelled by the obliquity correction of a (58°, a + 2b) prototype stretch twin
10.1107/S2053273317015042 2017-12-22 The and twinning modes were recently discovered by Ostapovets et al. [Philos. Mag. (2017), 97, 1088–1101] and interpreted as – double twins formed by the simultaneous action of two twinning shears. Another interpretation is proposed here in which the two conj... |
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The limit of application of the Scherrer equation
10.1107/S2053273317014929 2017-12-22 The Scherrer equation is a widely used tool to obtain crystallite size from polycrystalline samples. Its limit of applicability has been determined recently, using computer simulations, for a few structures and it was proposed that it is directly dependent on... |