Theoretical Solid State Physics

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

TECHNICAL SUMMARY: This award supports theoretical research and education in condensed matter physics and computational materials science. The PIs' projects cover a broad range of topics including the fields of semiconductors, metals, interfaces, superconductivity, nanotubes, magnetic systems, molecular junctions. These areas are addressed using previously developed and ongoing enhancements to theoretical and computational techniques based on quantum theory. These techniques enable accurate calculations for real materials. In particular, the ab initio pseudopotential method and total energy techniques are applied within the density functional formalism to compute ground-state properties. Excited-state (spectroscopic) phenomena are investigated using a self-energy approach based on the GW approximation for quasiparticle excitations and an ab initio two-particle Green's function method based on the Bethe-Salpter equation for optical excitations. Other studies employ variational and diffusion Monte Carlo approaches, molecular dynamics simulations, dielectric function methods, BCS theory, and density functional perturbation theory. Past successes include accurate predictions of properties and the existence of new materials and electronic structure calculations which allow band gap engineering approaches for technology. The present effort extends existing and adds several projects relate to understanding and predicting the properties of nanotubes, fullerenes, graphene, and other nanostructures; electronic, structural and mechanical properties of semiconductors, metals and novel materials; optical properties of nanostructures, defects and reduced-dimensional systems; electron transport through molecular junctions, atomic wires, and other nanostructures; and superconductivity, electron-phonon interactions, and magnetic effects. The broader impact of the effort includes the professional training of graduate students and post doctoral researchers associated with this group. The research, though basic, supports further development of advanced materials, especially those relevant to semiconductor technology and nanoscience. NON-TECHNICAL SUMMARY: This award supports theoretical research and education in condensed matter physics and computational materials science. The PIs' projects cover a broad range of topics including the fields of high performance materials and nanoscience. The research develops theoretical and computational techniques based on quantum theory to enable accurate calculations measured properties and the prediction of characteristics of materials that may yet be created in the laboratory. Such techniques have high reliability because the computations are based on theory developed from basic principles of physics. Specific projects include those related to understanding and predicting the properties of exotic materials such as fullerenes and technologically important nanostructures and semiconductor technology. Such properties include optical characteristics, material strength, and electrical properties, for example. The project is well suited to involve graduate students and researchers just beyond their graduate degrees, and so will contribute to a scientifically capable workforce.