Research

1. Study of excited state charge transfer process in MoS2/WS2 heterojunction

I studied the ultrafast hole transfer process in MoS2/WS2 heterojunction after excitation with TDDFT method. An analytical model with a dephasing bath of phonons was built to understand the physics behind the ultrafast coherent hole transfer and dephasing process. The experiment was well explained and a discontinuity phenomenon in the change transfer process was discovered by my model. A first-author paper was published on Nature Communications.

2. Parallelization of the real-time TDDFT code

A SIESTA based TDDFT-MD code was parallelized by myself with Message Passing Interface (MPI) in Fortran.

1). Replace LAPACK Library with ScaLAPACK Library

2). Distribute arrays to each node

3). Transfer variables (such as charge density) between nodes with MPI library


2. Discovery of new stacking and understanding of interlayer coupling of layered materials

Few-layer phosphorenes and black phosphorus was studied, and a new metastable stacking, named Aδ stacking, was identified. My tight binding code successfully explained the different behaviors of band splitting of few-layer phosphorenes with different stacking patterns, and this work was published on Nano Letters.

3. Defects in layered materials

Defects in topological materials, Bi2Se3, Bi2Te3 and battery material TiS2 were studied. Defects responsible for the native type conductivity were identified in our calculations and the primary role of spin orbit coupling in the formation of native defects was demonstrated.

4. Study of Weyl semimetals, Pentagon Carbon and carbon kagome lattice

New materials were discovered and their crystal structure, topological properties were studied with DFT and k∙p models.

5. Study of stark effect of excitons in InSe

Collaboration with experimentalists to understand the InSe PL peak shifting under external electric field. Formation energy and properties of various defects in InSe were studied with DFT.

6. Study of materials used in magnetic resonance imaging (MRI)

Collaboration with experimentalists to search for new materials to increase MRI resolution with X-ray Computed Tomography (CT)