Research Expertise and Interest
nanoscience, nuclear magnetic resonance, semiconductors, metals, physics, fullerenes, nanotubes, condensed matter theory, surfaces, defects, nanostructure materials, clusters, many-electron effects in solids
My group is engaged in research in condensed matter theory covering the areas of semiconductors, metals, surfaces, defects, nanostructure materials (such as fullerenes, nanotubes, and clusters), and many-electron effects in solids. The objective is to explain and predict the properties of materials using first-principles theories and computations.
Current Research Projects
A major interest of my group is nanoscience, in particular, systems involving nanotubes. Nanotubes are tubular structures, typically several nanometers in diameter and microns in length. These quasi-1D materials have novel properties (e.g., chiral currents and quantized conductance) of fundamental and practical interest. Systems being studied include defects on nanotubes, nanotube junctions, and nanopeapods. Various structures consisting of assembly of nanotubes and other nano-objects such as fullerenes and clusters are also being investigated.
The properties of a solid are dictated by the interacting electrons and ions in the system. Many properties are strongly affected by electron correlation effects. We are developing many-body perturbation methods and quantum Monte Carlo methods for studying these effects in real materials. In particular, first-principles one-particle and two-particle Green’s function approaches are used to compute quasiparticle energies and optical spectra for interpreting spectroscopic data and to predict phenomena such as photo-induced transformations. Quantum Monte Carlo techniques are used to determine ground-state properties of correlated electron systems. Many-electron effects (e.g., electron-hole interaction in optical processes) are particularly dominant in reduced dimensional systems such as surfaces, polymers, and clusters.
Nuclear magnetic resonance (NMR) is an important tool for studying the chemical, electronic and structural properties of liquids and solids. We have developed a method which allows the ab initio calculation of NMR chemical shifts in extended systems. This approach is applied to investigate crystals, amorphous solids, and liquids.
Hardness is a macroscopic property that is far from well understood. We are investigating the limits of the mechanical strength of solids, with the goals of understanding the physical origins of hardness and predicting new hard materials.