Molecular Dynamics Simulations of Single-Layer Molybdenum Disulphide (MoS2): Stillinger-Weber Parametrization, Mechanical Properties, and Thermal Conductivity

TL;DR

This paper develops a Stillinger-Weber potential for single-layer MoS2, enabling molecular dynamics simulations that reveal how edges, size, chirality, and strain influence its mechanical and thermal properties.

Contribution

The authors introduce a new empirical potential for MoS2 and systematically study its mechanical and thermal behavior under various conditions using molecular dynamics.

Findings

Edge effects reduce Young's modulus and thermal stability of nanoribbons.

Free edges lower melting temperature of MoS2 nanoribbons.

Uniaxial strain effectively tunes the thermal conductivity.

Abstract

We present a parameterization of the Stillinger-Weber potential to describe the interatomic interactions within single-layer MoS2 (SLMoS2). The potential parameters are fitted to an experimentally-obtained phonon spectrum, and the resulting empirical potential provides a good description for the energy gap and the crossover in the phonon spectrum. Using this potential, we perform classical molecular dynamics simulations to study chirality, size, and strain effects on the Young's modulus and the thermal conductivity of SLMoS2. We demonstrate the importance of the free edges on the mechanical and thermal properties of SLMoS2 nanoribbons. Specifically, while edge effects are found to reduce the Young's modulus of SLMoS2 nanoribbons, the free edges also reduce the thermal stability of SLMoS2 nanoribbons, which may induce melting well below the bulk melt temperature. Finally, uniaxial strain is found to efficiently manipulate the thermal conductivity of infinite, periodic SLMoS2.