47th Vietnam Conference on Theoretical Physics (VCTP47)
Hội nghị Vật lý lý thuyết Việt Nam lần thứ 47
Tuy Hòa, 14 August 2022

ProgrammeP.3  Poster, VCTP47 Date: Tuesday, 2 August 2022 Time: 08:30  10:00 Retrieval of structural information of monolayer transitionmetal dichalcogenides from exciton energy spectraLy Duy Nhat (1), Huynh Nguyen Thanh Truc (2) (1) HCMC University of Education; (2) Marie Curie High School We report a new procedure for retrieving the structural information, such as the reduced exciton mass, screening length, and dielectric constant of monolayer transitionmetal dichalcogenides (TMDs), from the experimental exciton energy spectra. The main idea is based on the fact that the Keldysh potential describes well the interaction between electron and hole. This interaction potential differs from the Coulomb potential at short distances due to the lowdimensional effect that makes it very sensitive to the structural parameters. We consider these structural quantities as free parameters and choose their appropriate values to fit the calculated exciton energy spectrum of 1s, 2s, 3s, and 4s states for the recently published experimental data [1]  [3]. For our purpose, we have built a computing program for exciton energies of monolayer TMDs in the magnetic field with high precision up to 15 decimal places by the FeranchukKomarov (FK) operator method [4]. The FK operator method combined with the LeviCivita transformation allows purely algebraic calculations with the creation and annihilation operators. One advantage of this work is to present the Keldysh potential through the Laplace transform that makes all the matrix elements calculated analytically. The exact analytic expressions of these matrix elements reduce computational resources significantly. Therefore, we can apply the method for ground and highly excited states. Especially, the program can be used for the states with nonzero magnetic quantum number m, better than the previous program working only for s states. [1] A. V. Stier, N. P. Wilson, K. A. Velizhanin, J. Kono, X. Xu, and S. A. Crooker, Magnetooptics of Exciton Rydberg States in a Monolayer Semiconductor, PRL 120 (2018) 057405. [2] M. Goryca et al., Revealing exciton masses and dielectric properties of monolayer semiconductors with high magnetic fields, Nat. Commun. 10 (2019) 4172. [3] J. Have, N. M. R. Peres, and T. G. Pedersen, Excitonic magnetooptics in monolayer transition metal dichalcogenides: From nanoribbons to twodimensional response, PRB 100 (2019) 1–10. [4] I. Feranchuk, A. Ivanov, VanHoang Le, A. Ulyanenkov, Nonperturbative Description of Quantum Systems, Springer, 2015. Presenter: Ly DuyNhat 
Institute of Physics, VAST

Center for Theoretical Physics 
Center for Computational Physics
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