Acta Crystallographica Section A: Foundations and Advances最新文献_第3页

Uncertainties of recalculated bond lengths, angles and polyhedral volumes as implemented in the Crystal Palace program for parametric crystal structure analysis. 重新计算的键长、角度和多面体体积的不确定性在水晶宫程序中实现，用于参数化晶体结构分析。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-05-01 Epub Date: 2025-04-29 DOI: 10.1107/S2053273325002682

Ross J Angel, Mattia L Mazzucchelli, Lisa Baratelli, Catherine F Schweinle, Tonci Balić-Žunić, Javier Gonzalez-Platas, Matteo Alvaro

{"title":"Uncertainties of recalculated bond lengths, angles and polyhedral volumes as implemented in the Crystal Palace program for parametric crystal structure analysis.","authors":"Ross J Angel, Mattia L Mazzucchelli, Lisa Baratelli, Catherine F Schweinle, Tonci Balić-Žunić, Javier Gonzalez-Platas, Matteo Alvaro","doi":"10.1107/S2053273325002682","DOIUrl":"https://doi.org/10.1107/S2053273325002682","url":null,"abstract":"Crystal Palace is a new Windows program for Parametric Analysis of Least-squares and Atomic Coordination with Estimated standard uncertainties (e.s.u.'s). The primary purpose of the program is to organize the refined structures from parametric structural studies (as a function of pressure or temperature or a series of compositions) for analysis of the structural trends, and the production of tables for publication without the risks associated with manual editing. The program reads structural information from one or more crystallographic information format (cif) files. It organizes the data by finding the structurally equivalent atoms in each structure and therefore can correctly organize structural information even if atom names or site occupancies are different, or the atom lists in the cif files are ordered differently. A major shortcoming of cif files as currently used is that they do not contain the full variance-covariance matrix from the structure refinement, but only the uncertainties of the individual positional parameters. Without the covariance of positional parameters, the e.s.u.'s of bond lengths and angles cannot be determined. Crystal Palace uses symmetry to estimate the major contributions to the covariance of atomic coordinates and thus realistic uncertainties of bond lengths, angles and polyhedral volumes. Crystal Palace also calculates various polyhedral distortion parameters and rigid-body corrections to bond lengths.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"81 Pt 3","pages":"202-210"},"PeriodicalIF":1.9,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12053496/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143956298","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

A note on the relation of anisotropic peak broadening with lattice symmetry in powder diffraction. 粉末衍射中各向异性峰展宽与晶格对称关系的注解。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-05-01 Epub Date: 2025-04-24 DOI: 10.1107/S2053273325003134

Piotr Fabrykiewicz

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George M. Sheldrick (1942-2025). 乔治·m·谢尔德里克（1942-2025）。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-05-01 DOI: 10.1107/S2053273325002931

Isabel Usón, Regine Herbst-Irmer

引用次数: 0

Report of the Executive Committee for 2023. 执行委员会2023年报告。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-05-01 Epub Date: 2025-04-15 DOI: 10.1107/S2053273324005990

引用次数: 0

Deconvoluting thermomechanical effects in X-ray diffraction data using machine learning. 利用机器学习反卷积x射线衍射数据中的热力学效应。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-01-31 DOI: 10.1107/S2053273325000403

Rachel E Lim, Shun Li Shang, Chihpin Chuang, Thien Q Phan, Zi Kui Liu, Darren C Pagan

{"title":"Deconvoluting thermomechanical effects in X-ray diffraction data using machine learning.","authors":"Rachel E Lim, Shun Li Shang, Chihpin Chuang, Thien Q Phan, Zi Kui Liu, Darren C Pagan","doi":"10.1107/S2053273325000403","DOIUrl":"10.1107/S2053273325000403","url":null,"abstract":"X-ray diffraction is ideal for probing the sub-surface state during complex or rapid thermomechanical loading of crystalline materials. However, challenges arise as the size of diffraction volumes increases due to spatial broadening and because of the inability to deconvolute the effects of different lattice deformation mechanisms. Here, we present a novel approach that uses combinations of physics-based modeling and machine learning to deconvolve thermal and mechanical elastic strains for diffraction data analysis. The method builds on a previous effort to extract thermal strain distribution information from diffraction data. The new approach is applied to extract the evolution of the thermomechanical state during laser melting of an Inconel 625 wall specimen which produces significant residual stress upon cooling. A combination of heat transfer and fluid flow, elasto-plasticity and X-ray diffraction simulations is used to generate training data for machine-learning (Gaussian process regression, GPR) models that map diffracted intensity distributions to underlying thermomechanical strain fields. First-principles density functional theory is used to determine accurate temperature-dependent thermal expansion and elastic stiffness used for elasto-plasticity modeling. The trained GPR models are found to be capable of deconvoluting the effects of thermal and mechanical strains, in addition to providing information about underlying strain distributions, even from complex diffraction patterns with irregularly shaped peaks.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"137-150"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11873812/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062184","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

Unit-cell parameters determination from a set of independent electron diffraction zonal patterns. 从一组独立的电子衍射带图确定单胞参数。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-01-31 DOI: 10.1107/S2053273325000300

Tatiana E Gorelik, Gerhard Miehe, Robert Bücker, Kaname Yoshida

引用次数: 0

A physical optics formulation of Bloch waves and its application to 4D STEM, 3D ED and inelastic scattering simulations. 布洛赫波的物理光学公式及其在4D STEM、3D ED和非弹性散射模拟中的应用。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-01-30 DOI: 10.1107/S2053273325000142

Budhika G Mendis

{"title":"A physical optics formulation of Bloch waves and its application to 4D STEM, 3D ED and inelastic scattering simulations.","authors":"Budhika G Mendis","doi":"10.1107/S2053273325000142","DOIUrl":"10.1107/S2053273325000142","url":null,"abstract":"Bloch waves are often used in dynamical diffraction calculations, such as simulating electron diffraction intensities for crystal structure refinement. However, this approach relies on matrix diagonalization and is therefore computationally expensive for large unit cell crystals. Here Bloch wave theory is re-formulated using the physical optics concepts underpinning the multislice method. In particular, the multislice phase grating and propagator functions are expressed in matrix form using elements of the Bloch wave structure matrix. The specimen is divided into thin slices, and the evolution of the electron wavefunction through the specimen calculated using the Bloch phase grating and propagator matrices. By decoupling specimen scattering from free space propagation of the electron beam, many computationally demanding simulations, such as 4D STEM imaging modes, 3D ED precession and rotation electron diffraction, phonon and plasmon inelastic scattering, are considerably simplified. The computational cost scales as {cal O}({N^2} ) per slice, compared with {cal O}({N^3} ) for a standard Bloch wave calculation, where N is the number of diffracted beams. For perfect crystals the performance can at times be better than multislice, since only the important Bragg reflections in the otherwise sparse diffraction plane are calculated. The physical optics formulation of Bloch waves is therefore an important step towards more routine dynamical diffraction simulation of large data sets.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"113-123"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11873815/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062165","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

Honeycombs - their variety, topology and symmetry. 蜂巢——它们的多样性、拓扑结构和对称性。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-02-14 DOI: 10.1107/S2053273325000889

Zbigniew Dauter, Mariusz Jaskolski

{"title":"Honeycombs - their variety, topology and symmetry.","authors":"Zbigniew Dauter, Mariusz Jaskolski","doi":"10.1107/S2053273325000889","DOIUrl":"10.1107/S2053273325000889","url":null,"abstract":"The double-layer honeycomb with hexagonal cells, three rhombic faces between the two layers and p3m1 layer space-group symmetry, used universally by honeybees, is often considered to be the most efficient (from the point of view of wax economy) and the only honeycomb manufactured by bees. However, another variant of a symmetric and periodic double-layer hexagonal honeycomb with two hexagons and two rhombi between the two layers and slightly better wax economy was discovered theoretically in 1964 by Fejes Tóth and found in nature some years later. The present work shows that there is yet another possibility, with the interface formed by one hexagon and two quadrangles, in addition to the trivial case with flat hexagonal cell bottoms and very poor wax economy. Moreover, we demonstrate that the geometry of the Fejes Tóth honeycomb can be optimized for even better wax economy. All the theoretical honeycomb types are derived using the principle of Dirichlet-domain construction and shown to have more and less symmetric variants. Wax economy is calculated for each case, confirming that indeed the modified Fejes Tóth honeycomb is the most efficient, while the trivial flat-bottom case is the least.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"159-166"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11873813/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143412457","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

Isogonal 1-periodic polycatenanes (chains). Transitivity and intransitivity of links. 同形1周期聚连环烷（链）。链接的及物性和非及物性。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-02-14 DOI: 10.1107/S2053273325001044

Michael O'Keeffe, Michael M J Treacy

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Symmetric 3-periodic polycatenanes: catenated rings, polyhedra and rods. 对称三周期聚连环烷：连环环、多面体和棒状。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2025-03-01 Epub Date: 2025-01-09 DOI: 10.1107/S2053273324012129

Michael O'Keeffe, Michael M J Treacy

引用次数: 0