Research Samples

Deformations drive structural phase transitions in monolayer materials.

We discover that certain two-dimensional transition metal dichalcogenides undergo structural metal-to-insulator phase transitions under tension. Our calculations reveal that MoTe2 transforms at the smallest tensile strains: between 0.3 and 3% under uniaxial conditions.

Electromechanical Bending in Boron Nitride Bilayers

Our work reveals a unique and manifestly nanoscale curvature-electric field coupling in boron nitride bilayers. This discovery hints at the possibility of electrically controlling or sensing the curvature of a membrane that is only 0.3 nm thick.

Hydrogen and Fluorine coadsorption leads to piezoelectricity in graphene.

Motivated by a search for electromechanical coupling in monolayer materials, we have discovered that two types of piezoelectricity can be engineered into graphene when it is chemically modified with H and F.

Quantum corrections bring 40% lower pressure onset for methane dissociaton under shock compression.

We have developed a methodology for atomistic simulations of shock compressed materials that, for the first time, incorporates semi-classical quantum nuclear effects self-consistently. In our new method, the quantum nuclear effects are achieved with almost no additional computational expense.

Intrinsic Piezoelectricity in Two-Dimensional Materials

Our research has discovered that many of the widely studied two-dimensional monolayer crystals have excellent piezoelectric properties, making them ideally suited for applications in nanoscale technology.

Engineered Piezoelectricity in Graphene

Piezoelectric effects can be engineered into non-piezoelectric graphene through the selective surface adsorption of atoms.

Amino acid containing complexes may form in a shocked comet

Multi-scale simulations reveal that shock compression of comet ice (water + small organic molecules) may generate biologically-relevant molecules. In collaboration with LLNL.

A new ultrafast probe of phase transformations

Molecular dynamics simulations of shock waves in CdSe show that THz frequency electromagnetic radiation can be emitted and used as an ultrafast passive probe of the wurtzite to rocksalt phase transformation. The radiation contains information about the transformation pathway.