Development and Application of a ReaxFF Reactive Force Field for Ni-Doped MoS$_2$

TL;DR

This paper introduces a new ReaxFF reactive force field for Ni-doped MoS2, enabling detailed molecular dynamics simulations of its properties, phase transitions, and behavior under various conditions.

Contribution

The authors developed and validated a novel ReaxFF force field specifically for Ni-doped MoS2, calibrated against DFT calculations, facilitating advanced reactive simulations.

Findings

Force field accurately reproduces DFT structural parameters.

Successfully models phase transition from amorphous to crystalline Ni-doped MoS2.

Enables simulation of sputtering deposition and annealing processes.

Abstract

The properties of $\mathrm{MoS_2}$ can be tuned or optimized through doping. In particular, Ni doping has been shown to improve the performance of $\mathrm{MoS_2}$ for various applications, including catalysis and tribology. To enable investigation of Ni-doped $\mathrm{MoS_2}$ with reactive molecular dynamics simulations, we developed a new ReaxFF force field to describe this material. The force field parameters were optimized to match a large set of density-functional theory (DFT) calculations of 2H-$\mathrm{MoS_2}$ doped with Ni, at four different sites (Mo-substituted, S-substituted, octahedral intercalation, and tetrahedral intercalation), under uniaxial, biaxial, triaxial, and shear strain. The force field was evaluated by comparing ReaxFF- and DFT-relaxed structural parameters, the tetrahedral/octahedral energy difference in doped 2H, energies of doped 1H and 1T monolayers, and doped 2H structures with vacancies. We demonstrated the application of the force field with reactive simulations of sputtering deposition and annealing of Ni-doped $\mathrm{MoS_2}$ films. Results show that the developed force field can successfully model the phase transition of Ni-doped $\mathrm{MoS_2}$ from amorphous to crystalline. The newly developed force field can be used in subsequent investigations to study the properties and behavior of Ni-doped $\mathrm{MoS_2}$ using reactive molecular dynamics simulations.