Abstract：

　　Understanding excited state phenomena is at the heart of many important materials problems, such as photovoltaics, photocatalysis, plasmonics and quantum information. In this talk, I will first give an overview of my recent research in computational materials science. I will then highlight our recent progress in developing accurate and efficient first-principles methods that enable us to probe electronic excitations in emerging materials. Among them, a subspace time-dependent density functional theory (TDDFT) method is developed which can compute both excitation energy and excited state forces accurately for systems containing up to a few thousand electrons. We have also developed a time-dependent orbital-free DFT method with which tens of thousands of electrons can be treated fairly accurately in metals. Combining these methods with non-adiabatic molecular dynamics, one can perform coupled electron-ion and exciton-ion dynamics where phonons are important in electron transitions and excitations. I’ll show how these first-principles methods can be brought to bear on critical scientific problems that are of broad practical interests, including charge separation and exciton diffusion in perovskite and organic solar cells, moiré excitons and their condensation in two-dimensional van der Waals heterostructures.   

Biosketch：

　　Prof. Lu received his Ph. D from Chinese Academy of Sciences while most of his Ph. D work was carried out in his current institution - California State University Northridge (CSUN). After a postdoc appointment at Harvard, Prof. Lu returned to CSUN as a faculty member in 2004 and was promoted to a full professor in 2009. He is the director of NSF-funded PREM center on Quantum Materials and the founding director of the Center of Excellence in Materials Innovation, both at CSUN. Prof. Lu spends significant research effort in developing first-principles based multiscale computational methods and has applied these methods to various materials problems. Some of the problems relevant to electronic excitations in 2D materials (e.g., moiré excitons) will be highlighted in the talk. His recent publications (since 2010) can be found at http://www.csun.edu/nsfprem/recent-publications-dr-lu.