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B3LYP and MP2 methods are used to study the hydroxylation and dehydrogenation of thymine at different sites in the presence of hydroxyl radicals (·OH). The MP2 method captures a feature in the reaction of thymine with hydroxyl radicals that the B3LYP method misses. A transition state exists in the hydroxylation of thymine at its C6 site, according to the MP2 calculations by Rongri Tan, Dongqi Wang, Lin Hu, and Feng-Shou Zhang on page 367. This is consistent with the experimental observation that there is a larger population for the C5-hydroxylated product than for the C6-hydroxylated product.