This CAREER award supports computational research and education that will advance accurate and efficient calculations of quasiparticle and optical excitations in a variety of bulk materials and nanostructures. Excited state properties of semiconductors and nanostructures are currently subjects of intensive investigation in response to future demand for energy-related optoelectronic applications, such as solar cells and solid-state lighting. A first-principles understanding of excited state properties of semiconductors and nanostructures would enable the full potential of these materials to be realized for technological applications. A quantitative first-principles description of excitations in solids including both electron-electron and electron-hole correlations also remains a major fundamental challenge. This research will address current difficulties in calculating the excited state properties of materials with the general goal of developing new methods and techniques for systems containing strongly localized electrons and improving the efficiency and convergence of excited state calculations. Specifically, the methodology development includes: (1) combined generalized Kohn-Sham and GW approaches for more accurate accounts of the effects of semicore electrons on the valence electronic properties, (2) new techniques to improve the convergence of the GW calculations, and (3) more efficient interpolation techniques for evaluating the kernel that appears in the Bethe-Salpeter equation. These new developments will then be applied to the study of excited state properties of important systems such as III-nitrides and II-oxides, including bulk materials and nanostructures, as well as defect-related excited state properties. The educational activities of this CAREER award include student training and new course development in computational materials science. A web-based interactive tool for visualizing various solid state properties will be also developed. This project will be incorporated into the successful ?Physics and Art? project in the Department of Physics at SUNY Buffalo, which targets both physics students and general public to promote physics education. The long-term goal of the outreach activities is to promote the awareness of the general public on the urgency of energy-related problems and research. This goal will be achieved by public presentations and demonstrations, as well as by establishing and nurturing international collaborations on energy-related research. NONTECHNICAL SUMMARY This CAREER award supports computational and theoretical research and education that will enable more accurate and efficient computer calculations of how materials produce and interact with light. The reliable calculation of optical properties of materials starting only from the identity of the constituent atoms and their arrangement remains a formidable challenge to the field. The methods and techniques to be developed in this research activity are aimed at overcoming these challenges. Computational tools and techniques developed will be applied to semiconductor materials and nanostructures which have energy-related applications such as solar cells and solid-state lighting. The research will help not only in providing an atomic-scale understanding of experiments, but also in exploiting the full potential of these materials in energy-related optoelectronic applications. The computational techniques and tools contribute to the cyberinfrastructure of the broader materials research community. The educational activities of this CAREER award include student training and new course development in computational materials science. A web-based interactive tool for visualizing various solid state properties will be also developed. This project will be incorporated into the successful ?Physics and Art? project in the Department of Physics at SUNY Buffalo, which targets both physics students and general public to promote physics education. The long-term goal of the outreach activities is to promote the awareness of the general public on the urgency of energy-related problems and research. This goal will be achieved by public presentations and demonstrations, as well as by establishing and nurturing international collaborations on energy-related research.
