Title: Born-Huang expansion and path-integral based computer simulations of condensed matters

Speaker:

Xin-Zheng Li

xzli@pku.edu.cn

School of Physics, Peking University, Beijing 100871, P. R. China

Time: 9:30 am, Wednesday, Mar. 18, 2020 (UTC/GMT+08:00) (following the first seminar)

Online venue: Zoom online meeting ID: 987 575 796

Abstract: Molecules and condensed matters are entities composed by interacting electrons and nuclei. Therefore, an ideal computer simulation of a poly-atomic system such as condensed matters needs to address both the electronic and the nuclear degrees of freedom accurately, as well as their couplings. Compared with the more and more accurate quantum treatments of the interacting electrons, theoretical descriptions of the nuclei still largely remain at the level classical mechanics or quantum mechanics within the harmonic approximation. In this talk, using Born-Huang expansion and path-integral molecular dynamics (PIMD) as the basic techniques, we explain our recent theoretical efforts on simulating how the quantum nature of nuclei can influence the properties of the condensed matters, with all unharmonic effects taken into account. To accommodate the requirements associated with each specific problem, PIMD was combined with different computer simulation methods in each application and some technical details of these methods will also be explained.

About the speaker

After finishing a postdoc in University College London, Prof. Xin-Zheng Li joined the School of Physics, Peking University in 2012 and got his tenure as an associate professor in 2017. He obtained his Ph.D from the theory department of the Fritz-Haber Institute of the Max-Planck Society, Berlin, in 2008. Before that, we finished his undergraduate and master studies in Wuhan University and in the Semiconductor Institute of the Chinese Academy of Sciences respectively in 2000 and 2003. He is a theoretician in computational condensed matter physics, with a special focus on the development and applications of first-principles methods. In this talk, he will explain to us some of his understandings of nuclear quantum effects in condensed matters, using Born-Huang expansion and the path-integral representation of quantum mechanics as the basic tools.