SE840: Formation routes for small inorganic interstellar dust precursors

Metal-containing oxides and silicates can form in the circumstellar envelopes (CSEs) of oxygen-rich asymptotic giant branch (AGB) stars, beginning from small diatomic hydrides and oxides. As these oxides condense into larger clusters, they can serve as the starting point for the formation of interstellar dust and other rocky bodies as they continue to grow. Reactions for the formation of small oxides containing aluminum, magnesium, and calcium are explored utilizing high-accuracy quantum chemical computations via CCSD(T)-F12b/cc-pVTZ-F12 (F12-TZ). Transition states along the reaction pathways are first optimized with B3LYP/aug-cc-pVTZ and followed with a F12-TZ single point energy. Additionally, for each reaction, temperature-dependent rate constants are computed using canonical variational transition state theory (CVT) and the B3LYP/aug-cc-pVDZ level of theory. These reactions yield thermodynamically and kinetically favorable routes of formation for various inorganic oxides following the form of X2-4O2-4H0-2 (X = Mg, Al, or Ca) at temperatures ranging from 100-1700 K.