Accurate force-field methodology capturing atomic reconstructions in transition metal dichalcogenide moiré systems

Abstract

In this work, a generalized force-field methodology for the relaxation of large moiré heterostructures is proposed. The force-field parameters are optimized to accurately reproduce the structural degrees of freedom of some computationally manageable cells relaxed using density functional theory. The parameters can then be used to handle large moiré systems. We specialize to the case of 2H-phased twisted transition-metal dichalcogenide homo- and heterobilayers using a combination of the Stillinger-Weber intralayer- and the Kolmogorov-Crespi interlayer-potential. Force-field parameters are developed for all combinations of MX${}_2$ for $\text{M}\in \{\text{Mo},\text{W}\}$ and $\text{X}\in \{\text{S},\text{Se},\text{Te}\}$. The results show agreement within 20 meV in terms of band structure between density functional theory and force-field relaxation. Using the relaxed structures, a simplified and systematic scheme for the extraction of the interlayer moiré potential is presented for both R- and H-stacked systems. We show that in-plane and out-of-plane relaxation effects on the moiré potential, which is made both deeper and wider after relaxation, are essential. An interpolation based methodology for the calculation of the interlayer binding energy is also proposed. Finally, we show that atomic reconstruction, which is captured by the force-field method, becomes especially prominent for angles below 4-5${}^{\circ }$, when there is no mismatch in lattice constant between layers.

11 pages, 12 figures. Accepted by and to be published in Physical Review B

References in corpus (10)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• 2D materials and van der Waals heterostructures
• Magnetic 2D materials and heterostructures
• Quasiparticle band structures and optical properties of strained monolayer MoS2 and WS2
• Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
• Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers
• Moiré-Bose-Hubbard model for interlayer excitons in twisted transition metal dichalcogenide heterostructures
• Theory of tunable flux lattices in the homobilayer moiré of twisted and uniformly strained transition metal dichalcogenides
• Twist versus heterostrain control of optical properties of moiré exciton minibands

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• Laterally Extended States of Interlayer Excitons in Reconstructed MoSe${}_2$/WSe${}_2$ Heterostructures
• Effective long-range attraction of moiré excitons under the influence of atomic reconstructions and anisotropic screening