Acta Crystallographica Section A: Foundations and Advances最新文献_第10页

Crystal diffraction prediction and partiality estimation using Gaussian basis functions. 使用高斯基函数进行晶体衍射预测和偏差估计。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 Epub Date: 2023-02-17 DOI: 10.1107/S2053273323000682

Wolfgang Brehm, Thomas White, Henry N Chapman

引用次数: 0

Twenty-Fifth General Assembly and International Congress of Crystallography, Prague, Czech Republic, 14-21 August 2021. 第二十五届大会暨国际晶体学大会，捷克共和国布拉格，2021年8月14日至21日。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 DOI: 10.1107/S205327332300058X

A T Ashcroft

引用次数: 0

Dynamical diffraction of high-energy electrons by light-atom structures: a multiple forward scattering interpretation. 光原子结构对高能电子的动态衍射：多重前向散射解释。

IF 1.9 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 Epub Date: 2023-02-09 DOI: 10.1107/S2053273322011779

Tarik R Drevon, David G Waterman, Eugene Krissinel

引用次数: 0

A fast two-stage algorithm for non-negative matrix factorization in smoothly varying data. 光滑变化数据中非负矩阵分解的快速两阶段算法。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 DOI: 10.1107/S2053273323000761

Ran Gu, Simon J L Billinge, Qiang Du

引用次数: 1

Dynamic tilting in perovskites. 钙钛矿的动态倾斜。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 DOI: 10.1107/S2053273322011949

Christopher M Handley, Robyn E Ward, Colin L Freeman, Ian M Reaney, Derek C Sinclair, John H Harding

引用次数: 1

A general force field by machine learning on experimental crystal structures. Calculations of intermolecular Gibbs energy with FlexCryst. 用机器学习研究实验晶体结构的一般力场。用FlexCryst计算分子间吉布斯能。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-03-01 DOI: 10.1107/S2053273323000268

Detlef Walter Maria Hofmann, Liudmila Nikolaevna Kuleshova

{"title":"A general force field by machine learning on experimental crystal structures. Calculations of intermolecular Gibbs energy with FlexCryst.","authors":"Detlef Walter Maria Hofmann, Liudmila Nikolaevna Kuleshova","doi":"10.1107/S2053273323000268","DOIUrl":"https://doi.org/10.1107/S2053273323000268","url":null,"abstract":"Machine learning was employed on the experimental crystal structures of the Cambridge Structural Database (CSD) to derive an intermolecular force field for all available types of atoms (general force field). The obtained pairwise interatomic potentials of the general force field allow for the fast and accurate calculation of intermolecular Gibbs energy. The approach is based on three postulates regarding Gibbs energy: the lattice energy must be below zero, the crystal structure must be a local minimum, and, if available, the experimental and the calculated lattice energy must coincide. The parametrized general force field was then validated regarding these three conditions. First, the experimental lattice energy was compared with the calculated energies. The observed errors were found to be in the order of experimental errors. Second, Gibbs lattice energy was calculated for all structures available in the CSD. Their energy values were found to be below zero in 99.86% of the cases. Finally, 500 random structures were minimized, and the change in density and energy was examined. The mean error in the case of density was below 4.06%, and for energy it was below 5.7%. The obtained general force field calculated Gibbs lattice energies of 259 041 known crystal structures within a few hours. Since Gibbs energy defines the reaction energy, the calculated energy can be used to predict chemical-physical properties of crystals, for instance, the formation of co-crystals, polymorph stability and solubility.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 2","pages":"132-144"},"PeriodicalIF":1.8,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9369469","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

Delone lattice studies in C 3, the space of three complex variables Delone格在c3中的研究，三个复变量的空间

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-01-31 DOI: 10.1107/s2053273323006198

L. C. Andrews, H. Bernstein

引用次数: 0

Measuring lattices 测量晶格

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-01-24 DOI: 10.1107/s2053273323004692

L. C. Andrews, H. Bernstein

引用次数: 0

Introduction of a weighting scheme for the X-ray restrained wavefunction approach: advantages and drawbacks. x射线约束波函数法的加权方案的介绍:优点和缺点。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-01-01 DOI: 10.1107/S2053273322010221

Giovanni Macetti, Alessandro Genoni

{"title":"Introduction of a weighting scheme for the X-ray restrained wavefunction approach: advantages and drawbacks.","authors":"Giovanni Macetti, Alessandro Genoni","doi":"10.1107/S2053273322010221","DOIUrl":"https://doi.org/10.1107/S2053273322010221","url":null,"abstract":"In a quite recent study [Genoni et al. (2017). IUCrJ, 4, 136-146], it was observed that the X-ray restrained wavefunction (XRW) approach allows a more efficient and larger capture of electron correlation effects on the electron density if high-angle reflections are not considered in the calculations. This is due to the occurrence of two concomitant effects when one uses theoretical X-ray diffraction data corresponding to a single-molecule electron density in a large unit cell: (i) the high-angle reflections are generally much more numerous than the low- and medium-angle ones, and (ii) they are already very well described at unrestrained level. Nevertheless, since high-angle data also contain important information that should not be disregarded, it is not advisable to neglect them completely. For this reason, based on the results of the previous investigation, this work introduces a weighting scheme for XRW calculations to up-weight the contribution of low- and medium-angle reflections, and, at the same time, to reasonably down-weight the importance of the high-angle data. The proposed strategy was tested through XRW computations with both theoretical and experimental structure-factor amplitudes. The tests have shown that the new weighting scheme works optimally if it is applied with theoretically generated X-ray diffraction data, while it is not advantageous when traditional experimental X-ray diffraction data (even of very high resolution) are employed. This also led to the conclusion that the use of a specific external parameter λJ for each resolution range might not be a suitable strategy to adopt in XRW calculations exploiting experimental X-ray data as restraints.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 1","pages":"25-40"},"PeriodicalIF":1.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10847366","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

Electron density and thermal motion of diamond at elevated temperatures. 高温下金刚石的电子密度和热运动。

IF 1.8 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2023-01-01 DOI: 10.1107/S2053273322010154

Jonas Beyer, Thomas Bjørn Egede Grønbech, Jiawei Zhang, Kenichi Kato, Bo Brummerstedt Iversen

{"title":"Electron density and thermal motion of diamond at elevated temperatures.","authors":"Jonas Beyer, Thomas Bjørn Egede Grønbech, Jiawei Zhang, Kenichi Kato, Bo Brummerstedt Iversen","doi":"10.1107/S2053273322010154","DOIUrl":"https://doi.org/10.1107/S2053273322010154","url":null,"abstract":"The electron density and thermal motion of diamond are determined at nine temperatures between 100 K and 1000 K via synchrotron powder X-ray diffraction (PXRD) data collected on a high-accuracy detector system. Decoupling of the thermal motion from the thermally smeared electron density is performed via an iterative Wilson-Hansen-Coppens-Rietveld procedure using theoretical static structure factors from density functional theory (DFT) calculations. The thermal motion is found to be harmonic and isotropic in the explored temperature range, and excellent agreement is observed between experimental atomic displacement parameters (ADPs) and those obtained via theoretical harmonic phonon calculations (HPC), even at 1000 K. The Debye temperature of diamond is determined experimentally to be ΘD = 1883 (35) K. A topological analysis of the electron density explores the temperature dependency of the electron density at the bond critical point. The properties are found to be constant throughout the temperature range. The robustness of the electron density confirms the validity of the crystallographic convolution approximation for diamond in the explored temperature range.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"79 Pt 1","pages":"41-50"},"PeriodicalIF":1.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9813686/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10869848","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