CFN Colloquium

"First principles modeling of electronic excitations: From basic understanding to materials applications"

Presented by Deyu Lu, Center for Functional Nanomaterials, Brookhaven National Laboratory,

Thursday, February 1, 2018, 4:00 pm — Bldg 735, CFN, Seminar Room, 2nd Floor

Electronic excitations are fundamental physical processes. Spectroscopic information, such as absorption and emission spectra, from electron or photon probes is crucial for materials characterization and interrogation, especially in the context of in situ studies of materials or processes under operando conditions. When experimental data are supplemented by first principles atomic modeling and state-of-the-art data analytics tools, a coherent physical picture emerges containing atomic level details of materials and insights derived from spectral signatures, which eventually allows us to establish the mechanistic understanding of the intriguing structure-property-function relationship.

In this talk, the significance of the first principles modeling of electronic excitations is highlighted with three examples. In the first example, we investigated the oxygen 1s core-level binding energy shift of bilayer silica films on Ru(0001) in the X-ray photoelectron spectroscopy (XPS) measurement. Our study revealed that the binding energy shift is an electrostatic effect caused by the interplay of the surface and interface dipole moments. In the second example, we applied ab intio X-ray absorption near edge structure (XANES) modeling for spinel lithium titanate (Li4/3Ti5/3O4), an appealing lithium ion battery material. We identified key spectral features as fingerprints for quantitative assessment of the structural transformation during lithiation. In the third example, we demonstrated that how machine learning algorithms can be combined with XANES modeling to predict the 3D structures of metal nanoparticles on-the-fly.

Hosted by: Mircea Cotlet

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