In this talk, I will discuss some recent progress and applications of the GW approach and its extensions to compute electronic excited-state properties, in particular of reduced-dimensional systems. This approach of many-body perturbation theory incorporates electron-electron interaction through the screened Coulomb interaction W, considering successively higher-number interacting particle Green’s functions. Quasiparticle excitations are computed within the GW approximation, and 2-particle excitations (e.g., those in optical responses) within the GW plus Bethe-Salpeter equation (GW-BSE) method. Many-electron effects are particularly important in reduced-dimensional systems, where together with symmetry, dimensionality and screening effects they can lead to important new concepts and novel phenomena. This is illustrated with several examples of current interest. Looking forward, I will briefly describe some on-going work on developing methods and codes for 3- and 4-particle correlated excitations which will address phenomena such as exciton-exciton interactions, formation of biexcitons and trions, decay of a single exciton into two excitons (fission), etc.<br/>This work was supported by U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences & Engineering Division, and by the National Science Foundation.

Excited-state phenomena in condensed matter: GW, GW-BSE, and beyond

254th National Meeting (2017)

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