Geometric Frustration in Isomerizations of Magic Sized Clusters

在化学系大分子、超分子和纳米化学（MSN）项目的支持下，康奈尔大学的Robinson教授和Dshemuchadse教授正在探索纳米团簇中的原子组织（少原子分子和大晶体之间缺失的联系）如何仅仅取决于它们的大小而改变。从纳米颗粒到日常块状材料，大多数材料的原子排列都是已知的。但对于比纳米粒子小的纳米团簇来说，表面效应对原子结构的稳定性有很大的影响。用实验技术和计算机模拟研究了魔术大小星系团原子稳定性的起源。纳米团簇结构的详细控制和精确操纵从一种原子排列到另一种原子排列的定义和快速转换的能力可以应用于光通信、能量收集或量子计算。Dshemuchadse教授和她的团队正在研究纳米粒子生长模拟的可视化，并将其作为互动教育在线材料提供给公众。此外，Robinson教授和Dshemuchadse教授正在设计一套关于晶体结构的演示套件，它向美国K-12教师展示了支配材料结构的排序原则。该项目的目的是确定无机纳米团簇和纳米颗粒的原子有序和异构化之间的关系。在硫化镉中，已经观察到具有所谓“神奇”大小的非常特殊的原子排列的纳米团簇改变了它们的结构。当镉硫族化合物被合成成离散簇大小，形成所谓的“神奇大小的纳米簇”时，它们能够在两种不同的结构之间连贯地转化，或者异构化。这个项目是研究由原子结构排列引起的几何挫折，以及这种挫折如何影响异构化。这种行为的起源正在通过纳米团簇合成和合成后修饰的实验研究，以及蒙特卡罗模拟来模拟不同团簇结构的稳定性。理解并能够控制纳米颗粒从局部簇到体晶行为的可逆交叉，可以使无机材料经历专为开关或传感行为设计的固-固过渡，这可以在能量收集或量子计算中找到应用。该团队正在通过创建自组装模拟的可视化和提供交互式在线材料，使纳米科学向公众开放。他们还设计了一个关于晶体结构及其与材料属性关系的教育演示套件，用于图书馆的外借模块。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Professors Robinson and Dshemuchadse at Cornell University are exploring how the atomic organization in nanoclusters—the missing link between few-atom molecules and larger crystals—can change, depending solely on their size. The atomic arrangement of most materials, from nanoparticles to everyday bulk materials, is known. But for nanoclusters, which are smaller than nanoparticles, surface effects can have a large influence on the stability of the atomic structure. The origin of the atomic stability in magic-sized clusters is investigated with experimental techniques and computer simulations. The detailed control of nanocluster structures and the ability to precisely manipulate the defined and rapid changeover from one atomic arrangement to another could have applications in optical communications, energy harvesting, or quantum computing. Professor Dshemuchadse and her group are working on the visualization of nanoparticle growth simulations to be made available to the public as interactive educational online materials. Additionally, Professors Robinson and Dshemuchadse are designing a demonstration kit on crystal structures, which illustrates the ordering principles that govern the structure of materials for K-12 teachers across the US.The objective of the project is to determine the relationship between the atomic ordering and isomerization in inorganic nanoclusters and nanoparticles. In cadmium sulfide, nanoclusters of very specific atomic arrangements of so-called "magic" sizes have been observed to transform their structure. When cadmium chalcogenides are synthesized into discrete cluster sizes, forming so-called "magic-sized nanoclusters", they are able to coherently transform between two distinct structures, or isomerize. This project is investigating the geometric frustration induced by the atomic structural arrangements, and how the frustration may influence isomerizations. The origin of this behavior is being investigated experimentally through nanocluster synthesis and post-synthetic modifications, as well as Monte-Carlo simulations to model the stability of different cluster configurations. Understanding and being able to control the reversible crossover from local-cluster to bulk-crystalline behavior in nanoparticles can lead to inorganic materials undergoing solid-solid transitions designed for switching or sensing behavior, which can find application in energy harvesting or quantum computing. The team is making nanoscience accessible to the public by creating visualizations of self-assembly simulations and providing interactive online materials. They are also designing an educational demonstration kit on crystal structures and their relationship with materials properties for lending library modules.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.