Gas-phase autoxidation of organics can generate highly oxygenated organic molecules (HOMs) and thus increase secondary organic aerosol production and enable new-particle formation. Here we explicitly represent the generation of HOMs via peroxy radical chemistry and resolve the products based on volatility and O : C. Using experimentally constrained assumptions about autoxidation and dimerization reactions, we see suppression of HOM formation under low-temperature and high-NO_x conditions.