Structures and electron detachment energies of uracil anions

Uracil and its radical anions were studied with second-order, many-body per turbation theory, coupled-cluster theory and electron propagator methods wi th large, diffuse, atom-centered basis sets. All structures were optimized and two minima were found for anionic forms: one corresponding to a (2)A', diffuse-bound state and another corresponding to a (2)A, non-planar, covale nt-bound state. The optimized (2)A' anionic structure is lower in energy th an the neutral form. The vertical electron detachment energy (VEDE) of this structure is very close to the experimentally observed value. A large, pos itive VEDE was found for the (2)A, covalent-bound anion. (C) 1999 Elsevier Science B.V. All rights reserved.