Coupled-cluster studies of alkylperoxy radicals: theory, properties, and reactions

Air pollution due to emissions from the combustion of fossil fuels is one of the biggest threats to human and environmental health. By interacting with tropospheric particles, complications due to these pollutants may be augmented by chain reactions and dispersive processes. Some of the most important chemical compounds in this regard are peroxy radicals (RO2), central to both combustion and atmospheric chemistries. Due to the reactive nature of RO2 and their subsequent reaction products, properties of these species have proven difficult to capture with experiment. High-level ab initio methods such as coupled-cluster (CC) theory have thus emerged as a complementary tool to experimental work on RO2. Herein, we report CC studies on the reactions and properties of RO2. First, we report work on the reactants, products, intermediates, and transition states of CH3O2 + NO, providing highly reliable predictions of the reaction mechanism. Then we investigate the X and A states of the conformers of C2H5O2, reporting properties of spectroscopic relevance (such as transition origins and fundamental vibrational frequencies).