Excitons in Flatlands: First-Principles Explorations
Dr. Gang Lu1, Professor of Physics
Co-PI(s): Dr. Xu Zhang1, Dr. Bryan M. Wong2
1: California State University Northridge, Northridge, CA 91330
2: University of California, Riverside, CA 92521
This Department of Energy (DOE) FAIR project aims to strengthen computational materials research and education at California State University Northridge (CSUN) through a partnership with the University of California at Riverside (UCR). As a non-R1 minority serving institution, CSUN is one of the largest comprehensive universities in the US with an annual enrollment of ~38,000 students. In close proximity to CSUN, UCR is an R1 minority serving institution with strong research and education programs in basic energy sciences. This FAIR project focuses on the development of first-principles computational methods based on time-dependent density functional theory (TDDFT) and the application of these methods to explore excitonic properties in two-dimensional (2D) van der Waals materials. The 2D van der Waals materials are emerging quantum materials with significant scientific interests and potential applications. Excitons are elementary excitations (i.e., correlated electron-hole pairs) in semiconductors and play crucial roles in optoelectronic properties of semiconducting materials.
Three objectives will be pursued in this FAIR project:
(1) Develop accurate, efficient, and robust real-time TDDFT methods with optimally tuned, screened and range-separated hybrid exchange-correlation functionals to study excitons in 2D van der Waals materials.
(2) Explore excitonic properties in 2D ferroelectric materials and their heterostructures that are both scientifically important and technologically relevant.
(3) Train next-generation materials scientists with diverse backgrounds and encourage them to pursue careers in science, technology, engineering and mathematics fields.
More specifically, the project supports the development of powerful and versatile first-principles methods that combine real-time TDDFT with non-adiabatic molecular dynamics to track real-time dynamics of excitonic states under ultrafast and/or strong electric fields. These methods will enable scientists to examine the interplay of electron excitation, polarization, and magnetism in 2D van der Waals materials and explore the coupling of charge, lattice, spin, and valley degrees of freedom in response to ultrafast laser fields. A number of important scientific problems will be addressed, including elucidation of excitonic properties in 2D ferroelectrics, and their heterostructures with 2D magnets and prediction of ferroelectric excitonic insulators. The project is ambitious, but if successful, it could lay the foundation for attosecond materials science and for critical technologies (optoelectronics, nonvolatile memories, spintronics, quantum information) relevant to the DOE mission.
This research was selected for funding by the Office of Science – Basic Energy Sciences
_____________________________________________________________________________________
