Computational approach is playing an ever increasing role in studies of materials for advanced technologies and in design of new functional materials. Computation bridges the gap between traditional theoretical and experimental methodologies in the field of science. It is able to provide the theoretical understandings to physical properties of various types of materials and is useful in identifying the underlying mechanisms of various physical processes. First principles methods based on density functional theory, in particular, have unprecedented predicting power because they do not require experimental input and all physical quantities are computed self-consistently by solving quantum mechanical equations. It is the state of the art approach for investigating properties of new materials and for designing new functional materials.

Much of our current research activities involve applications of first principles total energy calculations to various materials which are of importance to future technologies. On going projects include:
(1) high-k oxide and its interfaces with Si and metal;
(2) reconstruction of semiconductor surfaces and relaxation of metal interfaces;
(3) structures and properties of nanostructures;
(4) diluted magnetic semiconductors and spintronics materials
Most of these projects are in close collaboration with experimentalists.

When the size of materials is small enough so that it is comparable to the mean free path or wavelength of electrons that often lies in nano scale, the electronic properties of materials become different, and can no longer be deduced from those of corresponding bulk materials. To understand the unique size-dependence of properties of nano-materials by theoretical modeling and first-principles simulation is one of the key issues in nano-science. Our research is focused on theoretical modeling and simulation of various kinds of nano-materials that include thin films, nano-wires, clusters/molecules, and nano-junctions made of them. Particularly, we are interested in following directions.
1) Theoretical modeling of Josephson point contact
2) First-principles simulation of nano electronics/spintronics
3) Computer design of Graphene-based electronic devices
4) Computer simulation of chemical reactions catalyzed by surfaces

Life is a complex system. Motions of individual atoms and molecules in a living system obey physics laws and principles. However, how to connect the motion of atoms and molecules to life is probably the most challenging problem in life science. Biophysics is expected to play a unique role in solving this mystery and computation is an important tool in studying life science.

We are interested in understanding physical properties and behaviors of important biological molecular systems such as nucleic acid (DNA) and key biophysical processes. Some questions we are addressing include what are the origins of the unique physical properties of biomolecules, how we can manipulate a DNA molecule, how a DNA molecule behaves in a dense and congested state, how energy is transported along a DNA helix, and how a drug molecule interact with DNA. To answer these questions, we use computational techniques at different length and time scales in our study, on top of a synergetic experimental and theoretical approach. For example, ab initio methods are used to investigate the fundamental properties of biomolecules; molecular dynamics, Monte Carlo simulation, and mesoscopic simulation are used to study various biophysical processes; modeling and analytical approach are used to study the macroscopic behaviors. In the multiscale approach, information obtained at a lower level investigation can be used as input for a higher level simulation and prediction from a higher level simulation guides the lower level study.