Search for stable anions of uracil-water clusters. Ab initio theoretical studies

In this work we investigate the ability of the uracil water complex to form stable anionic systems; As the experimental evidence and theoretical calculations have indicated, the isolated uracil molecule can only attach an excess electron into a diffuse dipole-bound state, while some recent experiments suggest that the uracil water complex can form a more stable valence-type anion. In this work we demonstrate that it is possible to converge ab initio calculations of uracil .(H2O)3(-) to an equilibrium structure that is significantly different from the structure of the neutral cluster and that has a positive and remarkably significant vertical ionization potential. Apart from the valence anion, the uracil .(H2O)(3) complex can form a stable dipole-bound anion, but as the present calculations indicate the electron affinity, which corresponds to this attachment, is very small (13 meV). The structure of the dipole-bound anion is virtually identical with the structure of the neutral complex.