Suppr超能文献

基于密度泛函理论的分子动力学模拟对煅烧和水化 AlPO-11 结构的再研究*。

Revisiting the Structure of Calcined and Hydrated AlPO-11 with DFT-Based Molecular Dynamics Simulations*.

机构信息

Faculty of Geosciences, University of Bremen, Klagenfurter Straße 2-4, 28359, Bremen, Germany.

MAPEX Center for Materials and Processes, University of Bremen, 28359, Bremen, Germany.

出版信息

Chemphyschem. 2021 Oct 14;22(20):2063-2077. doi: 10.1002/cphc.202100486. Epub 2021 Aug 21.

Abstract

Published crystal structures of the AEL-type aluminophosphate AlPO-11 in its calcined form (space group ) show some peculiar features, such as unusually short Al-O and P-O bonds and near-linear Al-O-P angles. Although experimental evidence for the presence of dynamic disorder was presented, the nature of the associated distortions remained unresolved. In this study, ab initio molecular dynamics (AIMD) calculations in the framework of density functional theory (DFT) were employed to study the dynamic behaviour of this zeotype. At 100 K, static local distortions that break the symmetry are present in the time-averaged structures computed from the AIMD trajectories. At 300 and 500 K, the time-averaged structures approach symmetry. Although shortened Al-O and P-O bonds and near-linear Al-O-P angles were found in the average structures, an analysis of radial and angular distribution functions confirmed their absence in the instantaneous structures. This deviation is due to a precession-like motion of some oxygen atoms around the Al-P connection line, which moves their time-averaged positions closer to this line. In hydrated AlPO-11, some of the water molecules are coordinated to framework Al atoms, leading to an octahedral coordination of 1/5 of the Al sites. DFT optimisations and AIMD simulations on partially hydrated models delivered evidence for a preferential adsorption at the Al1 site. No dynamic disorder was observed for the hydrated form.

摘要

已发表的煅烧态 AEL 型磷酸铝 AlPO-11 的晶体结构(空间群 )显示出一些特殊的特征,例如异常短的 Al-O 和 P-O 键以及近乎线性的 Al-O-P 角度。尽管已经提出了存在动态无序的实验证据,但相关的变形的性质仍未得到解决。在这项研究中,采用密度泛函理论(DFT)的从头算分子动力学(AIMD)计算来研究这种沸石型的动态行为。在 100 K 时,从 AIMD 轨迹计算得到的时均结构中存在静态局部变形,破坏了 对称性。在 300 和 500 K 时,时均结构接近 对称性。尽管在平均结构中发现了缩短的 Al-O 和 P-O 键以及近乎线性的 Al-O-P 角度,但径向和角度分布函数的分析证实了它们在瞬时结构中不存在。这种偏差是由于一些氧原子围绕 Al-P 连接线的进动样运动引起的,这使得它们的时均位置更接近这条线。在水合 AlPO-11 中,一些水分子与骨架 Al 原子配位,导致 1/5 的 Al 位呈八面体配位。部分水合模型的 DFT 优化和 AIMD 模拟提供了证据,表明优先在 Al1 位吸附。未观察到水合形式的动态无序。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/e994/8596996/ef83edc58888/CPHC-22-2063-g003.jpg

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍。

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索

文档翻译

学术文献翻译模型,支持多种主流文档格式。

立即体验