Introduction:

My research group's interests including developing novel first-principle numerical methods for very large molecular system and investigating dynamics of complex systems including protein and bulk polymeric materials. A linear-scaling method is being developed in my group, and it is capable to simulate the dynamic response of systems containing up to thousands of atoms. New methods have been implemented to calculate the protein energy landscape and to identify pathways in biomolecules.

1) Very Large Scale Quantum Chemistry Calculation   

Localized-density-matrix (LDM) method has been developed to calculate electronic dynamics of very large molecular systems containing up to tens of thousand atoms. It has been implemented at semiempirical levels, and is being implemented with density functional theory. Electronic structures of polymer thin films, nanostructures, dendrimers, and proteins are under investigation. Inclusion of nuclei is expected to yield important information of these systems.

2)  Protein:  Simplicity vs Complexity

The emerging science of complexity seeks the simplicity of complex organisms. Proteins are between microscopic and macroscopic systems. They exhibit the characteristics of a complex system, and are on the boundary of the simple and complex. New techniques have been developed to evaluate the first principle free energy surfaces and to determine the charge transfer pathways of proteins. The calculations provide detailed understanding of dynamical processes in protein molecules, help to reveal the underlining general principles, and thus, contribute to the study of simplicity and complexity.