Computational Studies of Atmospheric Chemistry Intermediates Keith T Computational Studies of Atmospheric Chemistry Intermediates Keith T. Kuwata, Chemistry Department, Macalester College, Saint Paul, MN, 55105 We have studied reactions of the peroxy radical A and alkoxy radical B. RRKM/master equation simulations predict a significant fraction of A will undergo a 1,5-hydrogen shift promptly below 100 Torr (Fig. 1) and the microcanonical optimized multidimensional tunneling (mOMT) method predicts that tunneling accelerates the 1,4-hydrogen shift in B ten orders of magnitude at 200 K (Fig. 2). Fig. 2 A B Fig. 1 We have also predicted that carbonyl oxides (e.g. C) formed in isoprene ozonolysis rearrange to form novel dioxoles (e.g. D), and are currently calculating highly accurate constants for reactions of syn acetaldehyde oxide E. C D E