Molecular dynamics simulations of nanoparticle growth… and beyond

Pascal Brault (1)

1 GREMI - Groupe de recherches sur l'énergétique des milieux ionisés

As plasma processing is atomic and molecular by nature, simulations at the molecular level will be relevant for providing us with insight for core and interface plasma chemistry basic phenomena. Moreover, statistical averaging allows to provide/predict macroscopic data as reaction rates, diffusion coefficients, ... Among all the available molecular simulation tools, (reactive) molecular dynamics (MD) simulation technique is a good compromise between quantum mechanical and kinetic Monte-Carlo methods, especially due to the availability of robust and accurate reactive force fields [1]. MD are simulations are calculating the trajectories of a set of particles, by solving the appropriate set of Newton equation of motion. Initial conditions of MD simulations are selected for matching experimental conditions. The present talk will focus on the (reactive) growth of nanoparticles (NP) in gas aggregation source (GAS) powered by a magnetron plasma sputtering. Two approaches are described here: modelling the NP growth from a metal vapour in a (reactive gas) and modelling the sputtering and the entire GAS source in a single multiscale simulation. In the former case, the simulation box is composed of the plasma forming gas (Argon here), a metal vapour (Pd, Pt, Bi, Ni, Cu, or Au) considered as issued from sputtering) and if relevant a reactive (O2 here). The ratio of the plasma components is deduced from experiments [2, 3]. The composition and morphology of NPs are consistent with experimental findings, especially catalytic properties [4]. In the latter case, it is possible to describe the entire process of sputtering and NP growth and deposition using scaling arguments: it is enough to keep the experimental collision number in the MD simulation box [5]. References [1] E. C. Neyts and P. Brault, Plasma Process. Polym. 14 (2017) 1600145 [2] P. Brault, et al, Frontiers of Chemical Science and Engineering 13 (2019) 324 - 329 [3] W. Chamorro-Coral, et al, Plasma Process. Polym 16 (2019) 1900006 [4] P. Brault et al, J. Phys. Chem. C 123 (2019) 29656 [5] P. Brault, Frontiers in Physics 6 (2018) 59

Mots clés: Molecular dynamics simulation; plasma processing; nanoparticle growth; reactivity; reaxFF; LAMMPS

Domaines: Matériaux; Plasmas

Pascal Brault. Molecular dynamics simulations of nanoparticle growth… and beyond. 2020. ⟨hal-02518432⟩