New Reactive Force Field for Simulations of MoS₂ Crystallization

Abstract

We present a new reactive force field (ReaxFF) parameter set for simulations of Mo–S structures. We compare our parameterization to the state-of-the-art ones in their performance against density functional theory (DFT) benchmarks and MoS 2 crystallization simulations. Our new force field matches DFT data significantly better than any previously published force fields and provides a realistic layered MoS 2 structure in crystallization simulations. It significantly improves the state-of-the-art force fields, which tend to crystallize in the experimentally unknown rock-salt MoS structure. Therefore, our new force field is a good candidate for further development and inclusion of other practically relevant elements, such as O, C, N, and H, which can be used to study the formation and tribological or catalytical properties of molybdenum disulfide.

Friend or Foe? Revising the Role of Oxygen in the Tribological Performance of Solid Lubricant MoS2

“…As a point of comparison, sliding in a pure (O-free) MoS 2 model of the same size was studied. Due to the very strong tendency of MoS 2 to crystallize and form commensurate layers, a 2H-MoS 2 setup was chosen as the starting point. The outcomes of the tribological simulations (in terms of the sliding force vs the normal load) are shown in Figure d.…”

“…To gain more insights into the structure and sliding performance of amorphous Mo−S−O materials, we employed a newly developed Mo−S ReaxFF potential, 82 which was expanded to include oxygen. The modeled amorphous coating, shown in Figure S7, is a good depiction of the as-deposited amorphous Mo−S−O coating.…”

Development and Application of a ReaxFF Reactive Force Field for Ni-Doped MoS2

“…76 We started from two different parameter sets that were previously developed for S/Mo interactions, one reported in 2017 55 and the other reported in 2022. 61 The 2017 potential was developed specifically for single-layer MoS 2 , with a focus on its mechanical response with and without vacancies, and included parameters to model interactions between MoS 2 and oxygen. Then, the 2022 potential was developed by modifying the Mo/S parameters in the 2017 potential to better capture crystallization of MoS 2 in bilayer and bulk form.…”

“…The second stage was annealing the deposited Ni-doped MoS 2 film, following a simulation process similar to that used previously for the crystallization of undoped MoS 2 . 61 At this stage, the constraints on the lower-most atoms were removed, and the simulation cell height was set to the height of the reflective wall at 4.8 nm with the boundary condition in the zdirection changed to periodic to model bulk material. The annealing process was carried out by heating the model at the end of the deposition stage to 5000 K over 50 ps at a ramping rate of 100 K/ps.…”

“…Several force fields within the ReaxFF formalism, that captures the formation and breaking of chemical bonds, have been parametrized for MoS 2 as well. ,− These force fields have been used in simulations of crystallization, ,− active edge sites, creation of vacancies, ,, distribution and dynamics of defects, mechanical properties of MoS 2 monolayer heterostructures, − and tribological behavior of multilayer MoS 2 . However, to investigate Ni-doped MoS 2 , force field parameters that include the interactions between Ni and MoS 2 are needed, which is a challenge as new interactions are introduced and the dopant’s effect on the otherwise weak interlayer interactions must be described.…”