Excitonic effects on nonlinear optical responses from first principles

ORAL

Abstract



We develop an efficient ab initio approach to study second harmonic generation (SHG) and shift current including electron-hole interactions, and apply it to monolayer h-BN and MoS2. We find that for these two-dimensional materials, the strongest SHG response peaks are due to large oscillator strength of the corresponding exciton states and of inter-exciton couplings. The low-energy SHG resonant with the 1s excitonic states in monolayer MoS2, however, is not strong due to the lacking of bright 2p states as intermediate states. Selection rules for inter-exciton couplings are derived using angular quantum numbers of exciton envelope functions and their momentum derivatives. A comparison of these two materials suggests that strong trigonal warping is essential for large excitonic enhancement in hexagonal materials.

*Work done in Berkeley is supported by the U. S. Department of Energy and the National Science Foundation. YHC acknowledges support by th MOST and HCHC in Taiwan.

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Presenters

  • Yang-hao Chan

    • Academia Sinica
    • Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
    • Institute of Atomic and Molecular Sciences, Academia Sinica
    • Lawrence Berkeley National Laboratory

Authors

  • Yang-hao Chan

    • Academia Sinica
    • Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
    • Institute of Atomic and Molecular Sciences, Academia Sinica
    • Lawrence Berkeley National Laboratory

  • Steven G Louie

    • University of California at Berkeley
    • University of California, Berkeley
    • University Of California, Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley; Lawrence Berkeley National Lab
    • UC Berkeley
    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • UC berkeley
    • Lawrence Berkeley National Laboratory
    • Physics Department, UC Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • LBNL & UC Berkeley

  • Jiawei Ruan

    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley
    • UC Berkeley