Acta Crystallographica Section A: Foundations and Advances最新文献_第9页

Approximating lattice similarity. 近似网格相似性

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 Epub Date: 2023-07-24 DOI: 10.1107/S2053273323003200

Lawrence C Andrews, Herbert J Bernstein, Nicholas K Sauter

引用次数: 0

Perfect precise colorings of plane semiregular tilings. 完美精确的平面半规则瓷砖着色。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323006630

Manuel Joseph C Loquias, Rovin B Santos

引用次数: 0

Distances in the face-centered cubic crystalline structure applying operational research. 面心立方晶体结构中距离的应用运筹学研究。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323004837

Gergely Stomfai, Gergely Kovács, Benedek Nagy, Neşet Deniz Turgay, Béla Vizvári

引用次数: 0

Patch frequencies in rhombic Penrose tilings. 菱形彭罗斯平铺中的贴片频率。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323004990

Jan Mazáč

引用次数: 1

Background optimization of powder electron diffraction for implementation of the e-PDF technique and study of the local structure of iron oxide nanocrystals. 粉末电子衍射背景优化，实现e-PDF技术，研究氧化铁纳米晶的局部结构。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323005107

Naga Vishnu Vardhan Mogili, Nathália Carolina Verissimo, A M Milinda Abeykoon, Emil S Bozin, Jefferson Bettini, Edson Roberto Leite, João Batista Souza Junior

{"title":"Background optimization of powder electron diffraction for implementation of the e-PDF technique and study of the local structure of iron oxide nanocrystals.","authors":"Naga Vishnu Vardhan Mogili, Nathália Carolina Verissimo, A M Milinda Abeykoon, Emil S Bozin, Jefferson Bettini, Edson Roberto Leite, João Batista Souza Junior","doi":"10.1107/S2053273323005107","DOIUrl":"https://doi.org/10.1107/S2053273323005107","url":null,"abstract":"The local structural characterization of iron oxide nanoparticles is explored using a total scattering analysis method known as pair distribution function (PDF) (also known as reduced density function) analysis. The PDF profiles are derived from background-corrected powder electron diffraction patterns (the e-PDF technique). Due to the strong Coulombic interaction between the electron beam and the sample, electron diffraction generally leads to multiple scattering, causing redistribution of intensities towards higher scattering angles and an increased background in the diffraction profile. In addition to this, the electron-specimen interaction gives rise to an undesirable inelastic scattering signal that contributes primarily to the background. The present work demonstrates the efficacy of a pre-treatment of the underlying complex background function, which is a combination of both incoherent multiple and inelastic scatterings that cannot be identical for different electron beam energies. Therefore, two different background subtraction approaches are proposed for the electron diffraction patterns acquired at 80 kV and 300 kV beam energies. From the least-square refinement (small-box modelling), both approaches are found to be very promising, leading to a successful implementation of the e-PDF technique to study the local structure of the considered nanomaterial.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 5","pages":"412-426"},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10167564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Combinatorial aspects of the Löwenstein avoidance rule. Part III: the relational system of configurations. Löwenstein回避规则的组合方面。第三部分:配置关系体系。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323006174

Montauban Moreira de Oliveira, Jean Guillaume Eon

{"title":"Combinatorial aspects of the Löwenstein avoidance rule. Part III: the relational system of configurations.","authors":"Montauban Moreira de Oliveira, Jean Guillaume Eon","doi":"10.1107/S2053273323006174","DOIUrl":"https://doi.org/10.1107/S2053273323006174","url":null,"abstract":"This paper introduces a new method of determining the independence ratio of periodic nets, based on the observation that, in any maximum independent set of the whole net, be it periodic or not, the vertices of every unit cell should constitute an independent set, called here a configuration. For 1-periodic graphs, a configuration digraph represents possible sequences of configurations of the unit cell along the periodic line. It is shown that maximum independent sets of the periodic graph are based on directed cycles with the largest ratio. In the case of 2-periodic nets, it is necessary to draw a different configuration digraph for each crystallographic direction defining a linkage between neighbouring cells, a concept known as a binary relational system. The two possible systems are analysed in this paper: overrightarrow{bf{sql}} is associated to nets displaying linkages between unit cells along the directions 10 and 01, and overrightarrow{bf{hxl}} is associated to nets also displaying linkages between cells along the direction 11. For both kinds of nets, a maximum independent set is obtained as a homomorphic image from overrightarrow{bf{sql}} or overrightarrow{bf{hxl}} to the respective configuration system. The method is illustrated with some of the 2-periodic nets listed on the Reticular Chemistry Structure Resource site; it is shown that it provides a rigorous solution to the case of the net sdh that was not satisfactorily solved in Part II [Moreira de Oliveira, de Abreu Mendes & Eon (2022). Acta Cryst. A78, 115-127]. The method is extended to relational systems based on non-translational symmetry operations. The successive steps are then summarized and a simple application to the 3-periodic net qtz is discussed; analysis of zeolites and aluminosilicates may proceed along the same lines. It is shown that the new method enables the analysis of disordered distributions in periodic nets.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 5","pages":"463-479"},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10170157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimal estimated standard uncertainties of reflection intensities for kinematical refinement from 3D electron diffraction data. 三维电子衍射数据运动学精化中反射强度的最优估计标准不确定度。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323005053

Malak Khouchen, Paul Benjamin Klar, Hrushikesh Chintakindi, Ashwin Suresh, Lukas Palatinus

{"title":"Optimal estimated standard uncertainties of reflection intensities for kinematical refinement from 3D electron diffraction data.","authors":"Malak Khouchen, Paul Benjamin Klar, Hrushikesh Chintakindi, Ashwin Suresh, Lukas Palatinus","doi":"10.1107/S2053273323005053","DOIUrl":"https://doi.org/10.1107/S2053273323005053","url":null,"abstract":"Estimating the error in the merged reflection intensities requires a full understanding of all the possible sources of error arising from the measurements. Most diffraction-spot integration methods focus mainly on errors arising from counting statistics for the estimation of uncertainties associated with the reflection intensities. This treatment may be incomplete and partly inadequate. In an attempt to fully understand and identify all the contributions to these errors, three methods are examined for the correction of estimated errors of reflection intensities in electron diffraction data. For a direct comparison, the three methods are applied to a set of organic and inorganic test cases. It is demonstrated that applying the corrections of a specific model that include terms dependent on the original uncertainty and the largest intensity of the symmetry-related reflections improves the overall structure quality of the given data set and improves the final Rall factor. This error model is implemented in the data reduction software PETS2.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 5","pages":"427-439"},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10483590/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10176158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Algorithms for magnetic symmetry operation search and identification of magnetic space group from magnetic crystal structure. 基于磁晶体结构的磁对称运算搜索与磁空间群识别算法。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-09-01 DOI: 10.1107/S2053273323005016

Kohei Shinohara, Atsushi Togo, Isao Tanaka

{"title":"Algorithms for magnetic symmetry operation search and identification of magnetic space group from magnetic crystal structure.","authors":"Kohei Shinohara, Atsushi Togo, Isao Tanaka","doi":"10.1107/S2053273323005016","DOIUrl":"https://doi.org/10.1107/S2053273323005016","url":null,"abstract":"A crystal symmetry search is crucial for computational crystallography and materials science. Although algorithms and implementations for the crystal symmetry search have been developed, their extension to magnetic space groups (MSGs) remains limited. In this paper, algorithms for determining magnetic symmetry operations of magnetic crystal structures, identifying magnetic space-group types of given MSGs, searching for transformations to a Belov-Neronova-Smirnova (BNS) setting, and symmetrizing the magnetic crystal structures using the MSGs are presented. The determination of magnetic symmetry operations is numerically stable and is implemented with minimal modifications from the existing crystal symmetry search. Magnetic space-group types and transformations to the BNS setting are identified by a two-step approach combining space-group-type identification and the use of affine normalizers. Point coordinates and magnetic moments of the magnetic crystal structures are symmetrized by projection operators for the MSGs. An implementation is distributed with a permissive free software license in spglib v2.0.2: https://github.com/spglib/spglib.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 5","pages":"390-398"},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10483586/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10241965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Double-slit X-ray dynamical diffraction in curved crystals. 弯曲晶体中的双缝x射线动态衍射。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-07-01 DOI: 10.1107/S2053273323004345

Minas K Balyan

引用次数: 0

Crystallography of homophase twisted bilayers: coincidence, union lattices and space groups. 同相扭曲双分子层的晶体学：巧合、联合晶格和空间群。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-07-01 Epub Date: 2023-06-02 DOI: 10.1107/S2053273323003662

Denis Gratias, Marianne Quiquandon

{"title":"Crystallography of homophase twisted bilayers: coincidence, union lattices and space groups.","authors":"Denis Gratias, Marianne Quiquandon","doi":"10.1107/S2053273323003662","DOIUrl":"10.1107/S2053273323003662","url":null,"abstract":"This paper presents the basic tools used to describe the global symmetry of so-called bilayer structures obtained when two differently oriented crystalline monoatomic layers of the same structure are superimposed and displaced with respect to each other. The 2D nature of the layers leads to the use of complex numbers that allows for simple explicit analytical expressions of the symmetry properties involved in standard bicrystallography [Gratias & Portier (1982). J. Phys. Colloq. 43, C6-15-C6-24; Pond & Vlachavas (1983). Proc. R. Soc. Lond. Ser. A, 386, 95-143]. The focus here is on the twist rotations such that the superimposition of the two layers generates a coincidence lattice. The set of such coincidence rotations plotted as a function of the lengths of their coincidence lattice unit-cell nodes exhibits remarkable arithmetic properties. The second part of the paper is devoted to determination of the space groups of the bilayers as a function of the rigid-body translation associated with the coincidence rotation. These general results are exemplified with a detailed study of graphene bilayers, showing that the possible symmetries of graphene bilayers with a coincidence lattice, whatever the rotation and the rigid-body translation, are distributed in only six distinct types of space groups. The appendix discusses some generalized cases of heterophase bilayers with coincidence lattices due to specific lattice constant ratios, and mechanical deformation by elongation and shear of a layer on top of an undeformed one.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 4","pages":"301-317"},"PeriodicalIF":1.9,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10317138/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9750633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0