David Strubbe, UC Merced: Defects and dopants in materials: Thermodynamics, Raman Spectra, and the Spin-Flip Bethe-Salpeter Approach
Zoom Details
Seminar
2:00 pm - 3:00 pm
Zoom Link: For Zoom Information Please Contact: QF-admin@cnsi.ucsb.edu
Speaker
David A. Strubbe
Assistant Professor of Physics
UC Merced
Bio
David Strubbe received a BS in chemistry and physics from the University of Chicago in 2005. He received a Ph.D. in physics with a designated emphasis in nanoscale science and engineering from UC Berkeley in 2012, working with Steven Louie, and was awarded the NSF graduate fellowship. He did postdoctoral research in the MIT Department of Materials Science and Engineering with Jeff Grossman, and in 2016 joined the faculty at UC Merced as an assistant professor of physics. His research in condensed matter theory focuses on methods and applications of electronic structure calculations. He is affiliated with the chemistry and materials science graduate programs as well as physics and is a co-PI for the DOE-funded Consortium for High Energy Density Science and Center for Chemical Computation and Theory, and the NASA-funded Merced Nanomaterials Center for Energy and Sensing (MACES). He received the Cottrell Scholar Award from the Research Corporation for Science Advancement in 2020.
Abstract
Dopants are a critical way to tune the properties of materials and enable new functionalities. In this talk, first I will discuss explorations of Ni-doping of the 2D material MoS2, which can modulate mechanical and electronic properties as well as create new in-gap states. We have calculated the structure and energetics of Ni-doped MoS2 to identify the thermodynamic conditions for the formation of different structures. We find that intercalation is most favorable [1] and it causes a large increase in the interlayer interactions [2]. The Raman spectra of different doped structures have distinct features which can be used experimentally to identify them, which has been challenging by other techniques. Second, I will discuss a new approach to the calculation of the spin states of defect states, for which there is not currently a satisfactory method. The spin-flip Bethe-Salpeter equation is able to describe singlet and triplet states in molecules and the diamond NV- center defect and is promising for characterizing novel quantum defects.
[1] Phase Stability and Raman/IR Signatures of Ni-Doped MoS2 from Density-Functional Theory Studies
