讲座主题：自然轨道重正化群（NORG）和动力学平均场理论（DMFT）

主讲人：卢仲毅 教授

讲座时间：2021年4月25日16:00-17:00

讲座地点：北校区西大楼三区412报告厅

主讲人介绍：卢仲毅，中国人民大学理学院物理系主任、材料计算与物质模拟团队学科责任教授和召集人、中国人民大学特聘教授。1988年于北京邮电大学应用物理系获学士学位，1991年于中国科学院理论物理研究所获硕士学位，1996年于意大利国际高等研究院(SISSA)获博士学位，2007年获得国家级人才。主要从事电子结构计算方法及其并行化算法以及分子动力学模拟方法的研究以及这些方法在实际系统中的应用。曾获国家自然科学二等奖。

讲座内容：There are many novel quantum phenomena in strongly correlated electronic materials. How to understand and characterize them has always been one of the central topics in condensed matter physics. The DFT+DMFT electronic structure calculation method is considered to be the most powerful and promising method for studying strongly correlated electronic materials, which combines the first-principles electronic structure calculation based on the density functional theory (DFT) and the dynamical mean field theory (DMFT). Nevertheless, the DFT+DMFT calculation method now suffers the sign problem with its quantum Monte Carlo impurity solver, which seriously hinders the development and application of DFT+DMFT. On the other hand, the quantum renormalization group (RG) procedure is one of the most important and accurate approaches for studying interacting many-electron correlated systems, upon which we propose a new concept in the framework of natural orbitals so that we can generalize the RG into general orbital space, namely natural orbitals renormalization group (NORG). We show that the NORG takes a polynomial rather than exponential computational cost in the number of electron bath sites to solve low-energy states of a quantum impurity model. Moreover, the NORG can work on a quantum impurity model with any lattice topological structure. Actually, the effectiveness of the NORG is basically irrespective of a model's topological structure. Thus, the NORG is naturally appropriate for studying quantum cluster-impurity model. This makes the NORG be a natural impurity solver to dynamical mean field theory.

主办单位：物理与光电工程学院