Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 47: Poster Session - 2D Materials: Electronic Structure, Excitations, etc.
O 47.9: Poster
Tuesday, March 17, 2020, 18:15–20:00, P2/EG
In-plane anisotropy of the elastic properties of monolayer transition-metal dichalcogenides — •Juliane Mörsel, Pasquale Pavone, and Claudia Draxl — Humboldt-Universität zu Berlin, Physics Department and IRIS Adlershof, Germany
Monolayer transition metal dichalcogenides are characterized as two-dimensional materials with hexagonal symmetry. Therefore, the linear elastic properties of these materials are isotropic along the in-plane directions and can be described by only two independent second-order elastic constants (SOECs). The anisotropy of the structure influences, nevertheless, the non-linear elastic properties, which at small values of applied strain can be described in terms of three independent third-order elastic constants (TOECs). In this work, we present an ab-initio investigation of the anisotropic behavior of the elastic properties of MoS2, MoSe2, WeS2, and WeSe2 monolayers. The SOECs and TOECs are obtained from numerical derivatives of the total energies with respect to the applied Lagrangian strain. For this purpose, total-energy calculations are performed using density-functional theory as implemented in the full-potential all-electron package T1lmttbnexciting [1]. In order to explicitly exploit the anisotropic elastic behavior of these systems, we calculate the SOECs for non-equilibrium reference structures which are obtained by modifying the equilibrium configuration with uniaxial strains along the principal in-plane directions. Analysis of these results allows us to distinguish different regimes of nonlinearity.
[1] A. Gulans et al., J. Phys.: Condens. Matter 26 (2014) 363202