Overview of Research
First-principles calculations based on density-functional theory have proven to be an appealing method to deal with complex systems using only the given atoms and some initial guess atomic coordinates. Such a method can efficiently and reliably calculate the total energy, which is crucial in determining the most stable structure in order to study all relevant physical properties. My research interests mainly focus on, via this method, the theoretical study of fundamental properties (energy spectrum, surface reconstruction, magnetism, charge/orbital ordering, ferroelectricity, spin-frustration, topological insulator, etc) of atoms/clusters and materials. In addtion, I have an abiding interest in the development of new computational algorithms using the localized B-splines basis to extend the power of this method for the non-periodic dimension of small clusters, nanowires, and graphene. Recently, I also use the quantum Monte Carlo techniques to study real systems. These approaches could be regarded as a complementary to the density-functional mean-field theory since they give an accurate description of electron correlation effects. I have applied this method to the investigation for the stability of bi- and tri-positronium and related problems, which are very challenging in anti-particle physics.