Universal Interatomic Potentials with DFT for Understanding Orbital Localization in Polydimethylsiloxane-Amorphous Silica Nanocomposites

To investigate molecular orbital localization in polydimethylsiloxane (PDMS) amorphous silica nanocomposites, an approach that integrates first-principles with data-driven methods is introduced: Integrated Modeling and Prediction using <i>Ab initio</i> and Combined Trained potentials for orbital localization (IMPACT4OL). This approach is used to accelerate the identification of localized orbitals near the polymer-nanoparticle interface in polymer nanocomposites (PNC). To accelerate the structure generation, machine-learned interatomic potentials (MLIPs) are utilized to perform molecular dynamics studies for studying the interfacial region with quantum mechanical methods. To investigate the adsorption behavior, various cross-linking densities of PDMS are utilized. While cross-links have been shown to induce defect sites for deep traps, for a small degree of polymerization of PDMS, they hinder the surface adsorption and, thereby, the locations of localized orbitals, which, in turn, can serve as trap sites. The acceleration of orbital localization, especially in large model systems, using IMPACT4OL facilitates the elucidation of intricate mechanisms and could help advance the development of novel PNC-based insulators and electrets. Furthermore, our method introduces a new path to advance understanding of the conformational dynamics for polymer-nanoparticle interface science and engineering.