Intermolecular interactions and its effect within Cr³⁺-containing atmospheric particulate matter using molecular dynamics simulations

Efforts have been dedicated recently to monitor, quantify, and explore the effects of VOCs on Cr containing atmospheric particles. However, considering difficulties in real-time experimental measurements, several ambiguities remain in the atmospheric Cr chemistry. Herein, we use molecular dynamics simulations to investigate interactions of Cr³⁺ containing particles with three commonly present ‘additives’, ozone, benzene, and formaldehyde. Different scenarios with Cr⁺³ particles and the effect of air around particles are examined. Interestingly, we observed no direct interaction between Cr⁺³ and the three additives used. However, the presence of these additives alters Cr⁺³/water interactions. Further, we found that the diffusion of Cr⁺³ and the additives is fast, however the results indicate that chemistry within atmospheric particles is not diffusion controlled. Although the higher concentrations of additives compared to their solubility levels could be a limitation of this study, taken together, the results shed insights to molecular behavior of Cr⁺³ within atmospheric particles.