当前位置: X-MOL 学术J. Appl. Crystallogr. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Complex modeling for the quantification of nanoscale disorder using genetic algorithms, density functional theory and line-profile analysis
Journal of Applied Crystallography ( IF 6.1 ) Pub Date : 2020-07-30 , DOI: 10.1107/s1600576720008225
Robert J. Koch , Guangfang Li , Shubham Pandey , Simon R. Phillpot , Hui Wang , Scott T. Misture

A new, computationally efficient, complex modeling approach is presented for the quantification of the local and average atomic structure, nanostructure and microstructure of an Au0.25Cu0.75 alloy. High-resolution X-ray powder diffraction and whole pattern fitting show that the sample is phase pure, with isotropic lattice strain and a distribution of equiaxed crystallites of mean size 144 (11) nm, where each crystallite has on average four twin boundaries and an average of three deformation faults per four crystallites. Both small- and large-box model optimizations were used to extract local and long-range information from the pair distribution function. The large-box, 640 000-atom-ensemble optimization approach applied herein relies on differential evolution optimization and shows that the alloy has chemical short-range ordering, with correlation parameters of −0.26 (2) and 0.36 (8) in the first and second correlation shells, respectively. Locally, there is a 1.45 (8)% tetragonal distortion which on average results in a cubic atomic structure. The isotropic lattice strain is a result of atom-pair-dependent bond lengths, following the trend dAu—Au > dAu—Cu > dCu—Cu, highlighted by density functional theory calculations. This approach is generalizable and should be extensible to other disordered systems, allowing for quantification of localized structure deviations.

中文翻译:

使用遗传算法、密度泛函理论和线轮廓分析量化纳米级紊乱的复杂建模

提出了一种新的、计算效率高、复杂的建模方法,用于量化 Au0.25Cu0.75 合金的局部和平均原子结构、纳米结构和微观结构。高分辨率 X 射线粉末衍射和全图拟合表明样品是相纯的,具有各向同性的晶格应变和平均尺寸为 144 (11) nm 的等轴微晶分布,其中每个微晶平均有四个孪晶界和一个每四个微晶平均三个变形断层。小盒子和大盒子模型优化都用于从配对分布函数中提取局部和远程信息。此处应用的大箱 640 000 原子集合优化方法依赖于差异演化优化,并表明合金具有化学短程排序,在第一和第二相关壳中,相关参数分别为 -0.26 (2) 和 0.36 (8)。在局部,存在 1.45 (8)% 的四方畸变,平均导致立方原子结构。各向同性晶格应变是依赖于原子对的键长的结果,遵循趋势 dAu-Au > dAu-Cu > dCu-Cu,密度泛函理论计算突出显示。这种方法是可推广的,应该可以扩展到其他无序系统,允许对局部结构偏差进行量化。遵循趋势 dAu-Au > dAu-Cu > dCu-Cu,通过密度泛函理论计算突出显示。这种方法是可推广的,应该可以扩展到其他无序系统,允许对局部结构偏差进行量化。遵循趋势 dAu-Au > dAu-Cu > dCu-Cu,通过密度泛函理论计算突出显示。这种方法是可推广的,应该可以扩展到其他无序系统,允许对局部结构偏差进行量化。
更新日期:2020-07-30
down
wechat
bug