Stefan T. Bromley ^1,2*

• ¹ Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
• ² University of Barcelona, Barcelona, Catalonia, Spain

Silicate dust is found in a wide range of astrophysical environments. Nucleation of silicate dust, typically in circumstellar environments, likely involves molecular silicates and nanosilicates in grain growth processes. When fully formed silicate grains with sizes ~0.1 μm enter the interstellar medium, supernovae shockwaves cause collision-induced shattering which is predicted to redistribute a significant proportion of the dust mass into a huge population of ultrasmall species with diameters ranging from ~1 nm (molecular silicates) to a few nanometers (nanosilicates). This presumed population has thus far not been unambiguously confirmed by observation but is one of the main candidates for causing the anomalous microwave emission. By virtue of their extreme small size, nanosilicates and molecular silicates could exhibit significantly different properties to larger silicate grains, which could be of astrochemical and/or astrophysical importance. Herein, we briefly review the properties of these ultrasmall silicate dust species with a focus on insights arising from bottom-up atomistic computational modelling. Finally, we highlight how such methods also have the unique potential to predict observationally verifiable spectral features of nanosilicates, that may be discernible using the James Webb Space Telescope.