Ab initio methods for reactive potential surfaces

Case studies of ten reactions using a variety of standard electronic structure methods are presented. These case studies are used to illustrate the usefulness and shortcomings of these standard methods for various classes of reactions. Limited comparisons with experiment are made. The reactions studied include four radical–radical combinations, H + CH₃ → CH₄, CH₃ + CH₃ → C₂H₆, H + HCO → H₂CO and CH₃ + HCO → CH₃CHO, three abstraction reactions, H + HO₂ → H₂ + O₂, H + HCO → H₂ + CO and CH₃ + HCO → CH₄ + CO, a radical–molecule addition, H + HCCH → C₂H₃, and two molecular decompositions, H₂CO → H₂ + CO and CH₃CHO → CH₄ + CO. The electronic structure methods used are DFT, MP2, CCSD(T), QCISD(T), CASSCF, CASPT2, and CAS+1+2+QC.