Bond Order Potential for Two-Dimensional Stanene to Probe Thermal Transport Using Molecular Dynamics Simulations

Abstract

Recent realization of single layer tin (stanene) on Bi2Te3 substrate via molecular beam epitaxy has led to a surge in research into its fundamental properties, and the feasibility of using stanene for various energy and device applications. In particular, stanene has attracted lot of attention owing to its tremendous promise in topological insulation, large-gap 2D quantum spin hall states, lossless electrical conduction, enhanced thermoelectricity, and topological superconductivity. Most of the previous works on stanene have focused on its electronic properties; atomistic investigations on growth mechanisms (needed to guide synthesis), phonon transport (crucial for designing thermoelectrics), and thermo-mechanical behavior of stanene are scarce. This paucity is primarily due to lack of reliable and efficient potential models that can accurately capture atomic interactions in stanene. Here, we develop a bond-order potential (BOP) based on Tersoff formalism that can accurately capture bond breaking/formation events, structure, energetics, thermodynamics, phonon frequencies, thermal conductivity, and mechanical properties of single layer tin. We determine the BOP parameters by fitting to a training dataset containing (a) structure, (b) equation of state (energy vs area), (c) elastic constants, and (d) phonon dispersion of stanene obtained from our density functional theory calculations. For fitting, we employ a global optimization scheme based on genetic algorithms. Finally, we employed our newly developed BOP to study anisotropy in thermal conductivity of stanene sheets, temperature induced rippling, as well as dependence of anharmonicity and thermal conductivity on temperature. Figure Caption: Comparison of (a) phonon dispersion, and (b) phonon density of states for monolayer stanene predicted by our newly developed Tersoff potential with those obtained from density functional theory calculations Figure 1