Nanomaterials nowadays are widely applied in different technological fields and the interest in their large-scale production has grown accordingly. Si nanoparticles (NP), in particular, are considered to have a great potential for device developments in the semiconductor and photovoltaic industry. The bottom-up synthesis from the gaseous phase is particularly attractive because, avoiding the use of solvents, is generally considered more ecological and suitable for large-scale production. Synthesis from low temperature plasma begins to be used at industrial level, but the optimization of the production process for a synthesis aimed at the formation of well-defined NP is still an open problem. In the bottom-up synthesis process, the very basic bricks in the reactor are in general the individual atoms that end up forming NP through several concurrent processes such as nucleation, atomic deposition, aggregation, coagulation, sintering, coalescence, chemical reactivity, which occurs in the early stages of the synthesis process. Obtaining experimental information on the processes occurring in the plasma reactor at temperatures of thousands of degrees is rather complicated, and in this perspective information coming from numerical simulations are strongly needed. For this purpose, a recent protocol has been developed in our group taking advantage of a combination of first principle calculations and reactive molecular dynamics simulations within a recently granted project, NanoDome, which has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement n. 646121.

More in particular, this presentation will show how (i) accurate Reactive Force Fields describing materials like Silicon and Zinc Oxide have been derived on the basis of first principles (DFT) calculations; (ii) reactive molecular dynamics in realistic plasma conditions (very high temperature ranging from 1000 to 5000 K) have been used to simulate phenomena like nucleation of embryo-clusters, growth, interaction and sintering between aggregates in presence of buffer gases (both unreactive, like Argon, or reactive, like Hydrogen and Nitrogen) [1].

From these latter simulations it has been possible to extract important information to feed mesoscale models towards a real multi-scale protocol aimed to a full description of the evolution of the nanoparticle population.

[1] Barcaro et al., CRYSTALS 7, 54 (2017) | [2] Barcaro et al., J. Chem. Theory Comput. 13, 3854 (2017)