New ReaxFF Reactive Force Field Optimized for Phonon and Thermal Properties of Molybdenum Disulfide

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have demonstrated immense potential in various applications, including nanoelectronics, optoelectronics, sensing, and energy storage, owing to their exceptional electronic, optoelectronic, and chemical properties. Accurately characterizing the thermal properties of TMDs for further implementation necessitates computationally expensive large-scale atomic simulations that are not feasible using first-principles methods. In this study, we present the development of a reliable ReaxFF reactive force field, guided by extensive first-principles calculations. The new empirical force field exhibits a significant improvement in describing the phonon dispersion curve of 2D Molybdenum Disulfide (MoS2) systems compared to the previous ReaxFF force field, which primarily focused on characterizing vacancies and ripple defects in this system. Utilizing the new ReaxFF force field, we calculate the phonon thermal conductivity (κ_∞) of MoS₂ to be 72.68 WK^-1m^-1, which agrees well with reference calculations using the Stillinger-Weber (SW) and moment tensor potential (MTP), yielding κ_∞ values of 66.09 and 63.45 WK-1m-1, respectively. In contrast, the previous ReaxFF force field yielded a κ_∞value of 77.23 WK-1m-1. These results highlight the enhanced reliability of the optimized ReaxFF force field in predicting the thermal properties of 2D MoS₂ system and its potential for studying the thermal properties of large-scale defective MoS₂ systems. Furthermore, the methods developed in this work for MoS2 can be extended to other TMDs and emerging materials.