The alkoxy radicals and their anions: Structures and electron affinities

The optimized geometries and electron affinities of the alkoxy radicals have been examined using four hybrid Hartree-Fock/density functional methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities (with ZPVE correction), obtained at the DZP++ BP86 level of theory, are 1.80 eV (for C2H5O), 1.80 eV (a) and 1.92 eV (b) for the two isomers of C3H7O, 1.83 eV (a) and 1.97 eV (b) for the two isomers of C4H9O, and 1.83 eV (a), 1.97 eV (b), 2.02 eV (c), and 1.96 eV (d) for the four isomers of C5H11O, respectively. Compared with the experimental values, the average absolute error of the BP86 method is 0.05 eV. The BPW91 and BLYP functionals also give reasonable predictions, with average absolute errors of 0.13 and 0.13 eV, respectively.