Xu Zhang
California State University-Northridge, CA·Chemistry
Many technologies depend on what happens at the surface of a tiny crystal or at the interface between two atom-thin sheets. Two computational projects tackle these questions with first-principles theory, meaning calculations that start from the quantum mechanics of electrons rather than from fitted parameters.
- Fields
Chemistry
Materials Science
Physics
- Topics
nanocrystals
N-heterocyclic carbenes
NHC ligands
- Grants
- 2 known grants, through Jul 2027
What they work on
- Use density functional theory calculations and machine learning, alongside in-situ characterization, to explain how N-heterocyclic carbene ligands bind noble metal surfaces and thereby control nanocrystal size and exposed facets.
- Support colloidal synthesis of platinum, palladium, gold and silver nanocrystals with high-index, step-rich surfaces by predicting how independently tuned steric and electronic properties of the carbene ligands alter crystal formation.
- Relate the structure of high-index noble metal nanocrystal surfaces to their catalytic performance in carbon dioxide reduction and furfural reduction reactions.
- Develop a first-principles method based on time-dependent density functional perturbation theory to compute exciton band structures, ionic forces, non-adiabatic couplings and the exciton-phonon coupling matrix in semiconductors and insulators.
- Implement fully unconstrained noncollinear magnetism and multi-level parallelization so excitonic properties of materials with strong spin-orbit coupling can be calculated on massively parallel computers.
- Apply the new method to two-dimensional transition-metal dichalcogenide van der Waals heterostructures to resolve phonon-assisted interfacial charge and energy transfer and intralayer versus interlayer exciton-phonon interactions.
More about the research
One supports the design of molecules that control how metal nanocrystals grow, aiming at better catalysts. The other builds new methods to predict how light-excited electrons exchange energy with vibrating atoms in solids, which sets the efficiency of solar cells and light emitters.
Why it matters
Knowing how a ligand binds a metal surface would let chemists synthesize nanocrystals with the facets they want on purpose, which matters for catalysts that convert carbon dioxide or biomass-derived furfural into useful chemicals. Reliable predictions of exciton-phonon coupling could guide the design of photovoltaics, photocatalysts, photodetectors, light-emitting diodes and biosensors, especially devices built from stacked two-dimensional materials, by showing where excited-state energy is lost.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Wanyi Nie
University at Buffalo, NY·Materials Science
Grow and characterize heterostructures of chiral hybrid perovskites and 2D transition metal dichalcogenides to study interlayer excitons, electron–hole pairs spanning the interface.
Keji Lai
University of Texas at Austin, TX·Physics
Measure the effective permittivity of excitons in monolayer semiconductors using cryogenic laser-illuminated microwave impedance microscopy, a scanning probe that senses local electrical response under light.
Diana Qiu
Yale University, CT·Physics·Early-career
Develop ab initio software built on the GW plus Bethe–Salpeter equation approach that calculates how electrons in chiral hybrid perovskites absorb left- versus right-circularly polarized light (circular dichroism).
The school
California State University-Northridge: 4 labs on PI Pages, $27M a year on research, 11 research doctorates a year.
Reach out
A start for your email. Fill in the brackets.