Unified first-principles description of direct and phonon-assisted optical absorption

ORAL

Abstract

Current state-of-the-art ab initio approaches to study optical absorption can describe direct absorption processes for direct bandgap materials, and phonon assisted indirect absorption processes for indirect bandgap materials. One limitation of these approaches is that the formalism for phonon-assisted absorption becomes ill-defined for photon energies exceeding the direct band gap, therefore many materials where direct and indirect gaps are close in energy cannot be described adequately. In this talk, we present a new many-body formalism to capture both direct and phonon-assisted processes on the same footing. We demonstrate this approach by discussing a few test cases, such as silicon, gallium arsenide, and germanium.

*This work was primarily supported by the U.S. National Science Foundation, Grant NSF DMREF 2119555 (theory, implementation, calculations), and partially by the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0020129 (code refactoring).Computational resources were provided by the Texas Advanced Computing Center (TACC) at The University of Texas at Austin, the National Energy Research Scientific Computing Center (a DOE Office of Science User Facility supported under Contract No. DE-AC02-05CH11231), and the Argonne Leadership Computing Facility (a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357).

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Presenters

  • Sabyasachi Tiwari

    • The University of Texas at Austin

Authors

  • Sabyasachi Tiwari

    • The University of Texas at Austin

  • Emmanouil Kioupakis

    • University of Michigan

  • Feliciano Giustino

    • University of Texas
    • University of Texas at Austin
    • The University of Texas at Austin