Modeling of Metallic Nanoparticles and Their Environment
Metallic nanoparticles, particularly gold nanoparticles (GNPs), are nanometer-sized objects used in nanomedicine, catalysis, and imaging due to their tunable chemical, physical, and optical properties. Several experimental teams at ICP synthesize and characterize these nanoparticles under ionizing radiation to rationalize their various properties and understand the role of the chemical and biological environment. The ThéoSim group has developed a multi-scale molecular simulation strategy for GNPs over recent years, mimicking different environmental conditions that are relevant for experiments conducted at ICP. The complexity of the phenomena involved is partly due to dynamic interactions with surface ligands and the solvent. The challenge in simulating these objects includes both the size of the systems and the time scales required to obtain quantitative and precise data that can be compared with experimental results.

We have demonstrated through classical molecular dynamics simulations that the first solvation layer of water progressively reorganizes to form a two-dimensional extended hydrogen bond network as the nanoparticle size increases, simultaneously enhancing water-nanoparticle and water-water interactions [Tandiana2021a]. To advance further and address many-body effects, we implemented the GAL force field (collaborator: S. Steinmann), recently developed for interactions between water and metallic surfaces, into the Tinker-HP software to enable coupling with the polarizable AMOEBA force field, highlighting the importance of polarization effects in dynamic properties [Tandiana-Thèse2022]. Additionally, to study the dynamics of the interaction between the GNP and surface ligands, we investigated the adsorption of various organic molecules onto the GNP using DFT approaches coupled with topological and vibrational analyses. These studies revealed the non-covalent nature of the interactions between the ligand and the GNP, as well as the significant role of molecule orientation on the IR and Raman spectra, which can be correlated with experimental data obtained at ICP [Tandiana2022, Tandiana2021b].
Finally, DFT simulations have recently been conducted to aid in the interpretation of time-resolved spectroscopy experiments on ELYSE to identify intermediates in the catalytic reduction of CO2 adsorbed on metal nano-catalysts (Cu, Au, and Ni) [Jiang2023].
Collaborations
Cécile Sicard and Emilie Brun (CPSysBio, ICP), Mehran Mostafavi (TEMiC, ICP), Stephan Steinmann and Carine Michel (Laboratoire de Chimie, ENS Lyon).