The effect of the force chain network on sound propagation in a granular material is poorly understood. To quantitatively study these effects, we perform acoustics experiments in a two dimensional photoelastic granular material in which force chains are visible. We send acoustic pulses into the material from a point source and measure the effects of this pulse via two methods: accelerometers wi...

The recently synthesized freestanding fouratom-thick double-layer sheet of ZnSe holds great promise as an ultraflexible and transparent photoelectrode material for solar water splitting. In this work, we report theoretical studies on a novel three-atom-thick single layer sheet of ZnSe that demonstrates a strong quantum confinement effect by exhibiting a large enhancement of the band gap (2.0 eV...

To enable large-scale atomistic simulations of material processes involving chemical reactions, we have designed linear-scaling molecular dynamics (MD) algorithms based on an embedded divide-and-conquer (EDC) framework: first principles-based fast reactive forcefield (F-ReaxFF) MD; and quantum-mechanical MD in the framework of the density functional theory (DFT) on adaptive multigrids. To map t...