Professor of Computational Mineral Physics, Department of Earth Sciences, University of Cambridge

报告摘要：

The experimental art of x-ray crystallography is just over 100 years old. It's successes are widespread in sciences, and of considerable impact on the modern world. Once we know the crystal structure of a material we may feel we know everything about where the atoms are, but in many cases this is not so, because many materials show some degree of disorder over short distances. In these cases the local structure may show significant fluctuations away from the average structure given by Bragg scattering. Standard diffraction can tell us very little about local structure, because it is only contains information about mean positions. On the other hand, methods based on "total scattering" can provide much more detailed information about local structure.

The best measurement of local structure is a technique called "total scattering". This is exactly what is suggested by its name: it is a the full scattering of radiation by a material, including Bragg scattering and the diffuse scattering that spans the whole range of scattering vectors. The Fourier transform of the total scattering gives the "pair distribution function" (PDF) which can be thought of as a histogram of all the instantaneous distances between atoms. The PDF is the ideal fingerprint of local structure.

In this talk I will briefly describe methods to measure the PDF, and then discuss in detail how we use the Reverse Monte Carlo method to use the PDF, total scattering and Bragg scattering to generate large configurations of atoms that are consistent with these data. These configurations are consistent with information about the average structure and the atomic fluctuations given in the data. Over time I have become convinced that the PDF + RMC method can give unique insights into the local structures of disordered crystalline materials. I will illustrate the methods by discussing a number of recent examples.

报告人简介：

Martin Dove教授是世界级的材料学专家，任职于剑桥大学、伦敦玛丽女王大学等高等学府。其研究领域涵盖“刚性单元模式理论及应用”、“负热膨胀及相关性质的研究”、“玻璃的原子动力学与高压结构研究”、“中子散射和反向蒙特卡罗方法在材料原子尺度模型构建中的应用研究”、“高分子材料辐射损伤的动力学模拟”等。同时也是当前国际通用软件DL_POLY的主要负责人。Martin Dove教授在Science、PRL等知名期刊上发表过近400篇论文，引用次数超过1万次。此外，Martin Dove教授还编写过多本关于材料原子结构和动力学的经典书籍。

资料链接: https://pan.baidu.com/s/18JqbjGEwiTYFug279hMW-w 提取码: 9m64

邀请人：丁玮  82649477