Programme

P.51 -- Poster, VCTP-48

Date: Thursday, 3 August 2023

Time: 08:30 - 10:00

Second order of perturbation theory as an analytical description for energy spectra of exciton in monolayer transition-metal dichalcogenides

Hanh T. Dinh, Ngoc-Hung Phan, Duy-Nhat Ly, and Van-Hoang Le

Ho Chi Minh City University of Education, Ho Chi Minh City, Vietnam

Two-dimensional exciton has currently been a subject of intensive studies by both theoretical and experimental approaches. In particular, the exciton energy spectra for s-state excitons in monolayer transition-metal dichalcogenides (TMDCs) were calculated numerically in most of the works (see, for example, [1-3]). However, their analytical expressions are also required for some physical analyses [4-5]. The Keldysh potential (for the screened electron-hole interaction) was obligatorily modified to obtain the analytical solutions in these works. Therefore, solutions achieved directly from the Schrodinger equation with the exact Keldysh interaction are still of great interest. We report some results of the regulatory perturbation theory (PT) method to solve the Schrodinger equation for excitons in monolayer TMDCs. Combining the FK operator method with the conventional perturbation theory allows a free parameter to regulate the convergence rate of the perturbation series. Consequently, the second approximation order of PT with an optimum choice of the free parameter gives accurate exciton energies for the 1s state with a relative error of less than 1% compared to the exact numerical solutions. This result inspires us to use the solution obtained in the second order of PT as an analytical energy. We are continuing to apply this approach for higher excited states. [1] A. Chernikov et al., Phys. Rev. Lett, 113 (2014) 076802. [2] B. Zhu, X. Chen, and X. Cui, Scientific Reports 5 (2015) 9218. [3] Duy-Nhat Ly et al., Phys. Rev. B 107 (2023) 205304. [4] M. R. Molas et al., Phys. Rev. Lett. 123 (2019) 136801. [5] Hieu T. Nguyen-Truong, Phys. Rev. B 105 (2022) L201407.

Presenter: Dinh Thi Hanh