Problems of A and B excitonic peak in 2D MoS2 absorption spectrum

Deals with issues related to computation of optical spectra, solving the Bethe-Salpeter equation.

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pandachang97
Posts: 20
Joined: Mon Feb 19, 2024 11:06 pm

Problems of A and B excitonic peak in 2D MoS2 absorption spectrum

Post by pandachang97 » Mon Sep 29, 2025 10:03 pm

Hello Daniele,
I hope you are doing well. Recently, I am running BSE calculation of absorption spectrum of 2D MoS2. The DFT cal is done in the QE (lattice vector a=3.168 A, c=20 A, ecut=60 Ry, nbands=500, k-grid=27*27*1). Then, I have G0W0 and G1W1 calcultions (see the gw_try1.in in the attachment). Later, I followed the tutorial listed in the webcite of Yambo tutorial and three input files are attached. My problem is that I can not reproduce the A or B peak in the absorption spectrum at around 2.0 eV(I know I did not include spin-orbit coupling, there should be split of peaks at 2.0 eV, but there should be a single peak at around 2.0 eV. ). I can reproduce the absorption spectrum at around 3.0 eV. The convergence test of paprameters is the same as the nature paper mentioned. The absortion spectrum is belowImage. Please feel free to let me know the potential problems of my input files (e.g. the electric field direction or the GW calculations). Thank you so much and best regards,
Xin
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Xin Chang
Postdoc research @UT Austin

lyzhao
Posts: 59
Joined: Tue May 31, 2016 8:02 am

Re: Problems of A and B excitonic peak in 2D MoS2 absorption spectrum

Post by lyzhao » Mon Sep 29, 2025 11:08 pm

Dear Chang,
What is the number of electron?
% BSEBands
10 | 20 | # [BSK] Bands range
%
means there is at least 20 valence electrons in your 2D MoS2 system

Best regards.
Youzhao Lan
College of Chemistry and Materials Science,
Zhejiang Normal University,
Jinhua, Zhejiang, China.
HomePage: http://blog.sciencenet.cn/u/lyzhao

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