The objectives of our research have been to investigate the electronic structure of condensed matter, and to study its effects on the structural and dynamical properties of materials. For systems with translational symmetry, calculations are performed from first principles with no adjustable parameters. This has been made possible by advances in computational methods developed in the past decades. When these first-principles calculations are not feasible in some larger and more complicated systems, model calculations are used to identify the important features. The purposes of these studies are to provide unambiguous explanations for various interesting phenomena observed experimentally in clusters, solids, and surfaces, and to make reliable predictions of new material properties from microscopic quantum theories. Our theoretical efforts can be classified into two categories: 

(1) the study of the electronic and dynamical properties of technologically important materials, and 

(2) the development of new algorithms and calculational methods in studying materials properties using quantum mechanics.