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.
–
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