Acta Crystallographica Section A: Foundations and Advances最新文献_第8页

Hierarchical topological analysis of crystal structures: the skeletal net concept. 晶体结构的层次拓扑分析:骨架网的概念。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2024-01-01 DOI: 10.1107/S2053273323008975

Olga A Blatova, Vladislav A Blatov

{"title":"Hierarchical topological analysis of crystal structures: the skeletal net concept.","authors":"Olga A Blatova, Vladislav A Blatov","doi":"10.1107/S2053273323008975","DOIUrl":"10.1107/S2053273323008975","url":null,"abstract":"Topological analysis of crystal structures faces the problem of the `correct' or the `best' assignment of bonds to atoms, which is often ambiguous. A hierarchical scheme is used where any crystal structure is described as a set of topological representations, each of which corresponds to a particular assignment of bonds encoded by a periodic net. In this set, two limiting nets are distinguished, complete and skeletal, which contain, respectively, all possible bonds and the minimal number of bonds required to keep the structure periodicity. Special attention is paid to the skeletal net since it describes the connectivity of a crystal structure in the simplest way, thus enabling one to find unobvious relations between crystalline substances of different composition and architecture. The tools for the automated hierarchical topological analysis have been implemented in the program package ToposPro. Examples, which illustrate the advantages of such analysis, are considered for a number of classes of crystalline substances: elements, intermetallics, ionic and coordination compounds, and molecular crystals. General provisions of the application of the skeletal net concept are also discussed.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"65-71"},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89716120","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

Deep learning applications in protein crystallography. 深度学习在蛋白质晶体学中的应用。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2024-01-01 DOI: 10.1107/S2053273323009300

Senik Matinyan, Pavel Filipcik, Jan Pieter Abrahams

引用次数: 0

Isogonal 2-periodic polycatenanes: chain mail. 异角2周期聚连环烷:链甲。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2024-01-01 DOI: 10.1107/S2053273323009543

Michael O'Keeffe, Michael M J Treacy

引用次数: 0

Professor Dr Hendrik (Henk) Schenk (1939–2023) 亨德里克（亨克）-申克博士教授（1939-2023）

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-12-08 DOI: 10.1107/s2053273323010379

Céleste A. Reiss

引用次数: 0

Isogonal embeddings of interwoven and self-entangled honeycomb (hcb) nets and related interpenetrating primitive cubic (pcu) nets. 交织自纠缠蜂窝（hcb）网络和相关的互穿原始立方体（pcu）网络的等角嵌入。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-10-26 DOI: 10.1107/S2053273323008495

Michael O'Keeffe, Michael M J Treacy

引用次数: 0

An efficient system matrix factorization method for scanning diffraction based strain tensor tomography. 基于扫描衍射的应变张量层析的有效系统矩阵分解方法。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-09-29 DOI: 10.1107/S2053273323008136

Axel Henningsson, Stephen A Hall

{"title":"An efficient system matrix factorization method for scanning diffraction based strain tensor tomography.","authors":"Axel Henningsson, Stephen A Hall","doi":"10.1107/S2053273323008136","DOIUrl":"10.1107/S2053273323008136","url":null,"abstract":"Diffraction-based tomographic strain tensor reconstruction problems in which a strain tensor field is determined from measurements made in different crystallographic directions are considered in the context of sparse matrix algebra. Previous work has shown that the estimation of the crystal elastic strain field can be cast as a linear regression problem featuring a computationally involved assembly of a system matrix forward operator. This operator models the perturbation in diffraction signal as a function of spatial strain tensor state. The structure of this system matrix is analysed and a block-partitioned factorization is derived that reveals the forward operator as a sum of weighted scalar projection operators. Moreover, the factorization method is generalized for another diffraction model in which strain and orientation are coupled and can be reconstructed jointly. The proposed block-partitioned factorization method provides a bridge to classical absorption tomography and allows exploitation of standard tomographic ray-tracing libraries for implementation of the forward operator and its adjoint. Consequently, RAM-efficient, GPU-accelerated, on-the-fly strain/orientation tensor reconstruction is made possible, paving the way for higher spatial resolution studies of intragranular deformation.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"542-549"},"PeriodicalIF":1.9,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10626655/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41091550","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

Prices of IUCr journals. IUCr期刊的价格。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-09-25 DOI: 10.1107/S2053273323008094

A M Stanley

引用次数: 0

A novel algorithm for calculation of Fourier and asymmetric units. 一种计算傅立叶和不对称单位的新算法。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-09-25 DOI: 10.1107/S2053273323007714

Frantisek Pavelcik

引用次数: 0

Site-occupancy factors in the Debye scattering equation. A theoretical discussion on significance and correctness. 德拜散射方程中的场地占用系数。关于意义和正确性的理论讨论。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-11-02 DOI: 10.1107/S2053273323008446

Fabio Ferri, Maria Chiara Bossuto, Pietro Anzini, Antonio Cervellino, Antonietta Guagliardi, Federica Bertolotti, Norberto Masciocchi

{"title":"Site-occupancy factors in the Debye scattering equation. A theoretical discussion on significance and correctness.","authors":"Fabio Ferri, Maria Chiara Bossuto, Pietro Anzini, Antonio Cervellino, Antonietta Guagliardi, Federica Bertolotti, Norberto Masciocchi","doi":"10.1107/S2053273323008446","DOIUrl":"10.1107/S2053273323008446","url":null,"abstract":"The Debye scattering equation (DSE) [Debye (1915). Ann. Phys. 351, 809-823] is widely used for analyzing total scattering data of nanocrystalline materials in reciprocal space. In its modified form (MDSE) [Cervellino et al. (2010). J. Appl. Cryst. 43, 1543-1547], it includes contributions from uncorrelated thermal agitation terms and, for defective crystalline nanoparticles (NPs), average site-occupancy factors (s.o.f.'s). The s.o.f.'s were introduced heuristically and no theoretical demonstration was provided. This paper presents in detail such a demonstration, corrects a glitch present in the original MDSE, and discusses the s.o.f.'s physical significance. Three new MDSE expressions are given that refer to distinct defective NP ensembles characterized by: (i) vacant sites with uncorrelated constant site-occupancy probability; (ii) vacant sites with a fixed number of randomly distributed atoms; (iii) self-excluding (disordered) positional sites. For all these cases, beneficial aspects and shortcomings of introducing s.o.f.'s as free refinable parameters are demonstrated. The theoretical analysis is supported by numerical simulations performed by comparing the corrected MDSE profiles and the ones based on atomistic modeling of a large number of NPs, satisfying the structural conditions described in (i)-(iii).","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"587-596"},"PeriodicalIF":1.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10626651/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71418681","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

Chiral spiral cyclic twins. II. A two-parameter family of cyclic twins composed of discrete circle involute spirals. 手性螺旋环状孪晶。二、由离散圆渐开线螺旋组成的双参数循环孪晶族。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-11-01 Epub Date: 2023-10-31 DOI: 10.1107/S2053273323008276

Wolfgang Hornfeck

{"title":"Chiral spiral cyclic twins. II. A two-parameter family of cyclic twins composed of discrete circle involute spirals.","authors":"Wolfgang Hornfeck","doi":"10.1107/S2053273323008276","DOIUrl":"10.1107/S2053273323008276","url":null,"abstract":"A mathematical toy model of chiral spiral cyclic twins is presented, describing a family of deterministically generated aperiodic point sets. Its individual members depend solely on a chosen pair of integer parameters, a modulus m and a multiplier μ. By means of their specific parameterization they comprise local features of both periodic and aperiodic crystals. In particular, chiral spiral cyclic twins are composed of discrete variants of continuous curves known as circle involutes, each discrete spiral being generated from an integer inclination sequence. The geometry of circle involutes does not only provide for a constant orthogonal separation distance between adjacent spiral branches but also yields an approximate delineation of the intrinsically periodic twin domains as well as a single aperiodic core domain interconnecting them. Apart from its mathematical description and analysis, e.g. concerning its circle packing densities, the toy model is studied in association with the crystallography and crystal chemistry of α-uranium and CrB-type crystal structures.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"570-586"},"PeriodicalIF":1.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10626652/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71409833","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