理学院数理讲坛（2017年第54讲）
报告题目： An Introduction to Density matrix renormalization group method and its applications
报告人： 王孝群教授/杰青
单 位： 上海交通大学
报告时间：2017年12月9日（星期六）10:00
报告地点：阳明学院303
报告摘要：
The recent renaissance of black phosphorus (BP) as a two-dimensional (2D) layered material has generated tremendous interest, but its unique structural characters underlying many of its outstanding properties still need elucidation. Here we report Raman measurements that reveal an ultralow-frequency collective compression mode (CCM) in BP, which is unprecedented among similar 2D layered materials. This novel CCM indicates an unusually strong interlayer coupling, and this result is quantitatively supported by a phonon frequency analysis and first-principles calculations. Moreover, the CCM and another branch of low-frequency Raman modes shift sensitively with changing number of layers, allowing an accurate determination of the thickness up to tens of atomic layers, which is considerably higher than previously achieved by using high-frequency Raman modes. These findings offer fundamental insights and practical tools for further exploration of BP as a highly promising new 2D semiconductor.
报告人简介：
王孝群教授，现任上海交通大学物理与天文系教授,杰青, “和创新团队发展计划”创新团队负责人。2003年06月至2013年12月中国人民大学物理系系主任,2013年12月至2017年6月任上海交通大学物理与天文学院院长。研究兴趣：低维强关联、介观系统性质的电子、磁性和输运特性以及量子信息等方面的理论研究；一些数值模拟方法的探讨、发展与应用。