Novel Structure Representation and Comparison for Cluster, Quasicrystal, and Crystal
Prof. Yu-Jun Zhao
Department of Physics, South China University of Technology

Efficient structure recognition and comparison provides us not only an insight of the intrinsic structures but also a novel approach to material design, in particular in the age of Big Data. Here we introduce an extended distance matrix approach and a minimum vertex-type sequence indexing scheme to study the geometric configuration and its comparison. It is shown that the positions of all atoms in the eigen-space can be specified precisely by their eigen-coordinates, while the refined atomic eigen-subspace projection array is demonstrated to be a competent invariant in structure comparison. A complete set of atomic EPFs constitute an intrinsic representation of molecular conformation or a local structural environment in a periodical system, based on which the interatomic EPF distance and the EPF distance between two configurations can be reasonably defined. Exemplified with a few cases, the intermolecular EPF distance shows exceptional rationality and efficiency in structure recognition, comparison, as well as potential energy surface construction.

For quasicrystals, their detailed atomic structures have been an open question for decades. We present a quasilattice-conserved molecular dynamics method (quasiMD), with particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni (d-Al-Co-Ni), we propose a more stable atomic structure model based on Penrose quasilattice and our quasiMD simulations. In particular, “rectangle-triangle”' rules are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.

About the Speaker

赵宇军, 1994年、1999年分别获浙江大学物理系学士和博士学位, 期间于1998年在日本静冈大学电子工程系学习一年; 1999年至2004年分别于美国西北大学和再生能源国家实验室(NREL)从事博士后研究; 2005至2006年于美国硅谷的NanoStellar公司任研究员; 2006年年底作为学校"百人计划"特聘教授于华南理工大学物理系任教, 现担任中国计算物理学会常务理事。赵宇军教授主要从事晶体缺陷和掺杂理论, 以及过渡金属表面的催化机制研究, 近期又开展了结构识别和比较方面的工作。先后主持了多项国家、省部级科研项目, 并入选2008年教育部新世纪优秀人才支持计划。至今, 赵宇军教授已在国际主流学术刊物上发表论文100余篇, 引用超过2000多次。

2018-12-13 10:00 AM
Room: A403 Meeting Room
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