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 theoret ical calculations have indicated, the isolated uracil molecule can onl y attach an excess electron into a diffuse dipole-bound state, while s ome 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 str ucture of the neutral cluster and that has a positive and remarkably s ignificant vertical ionization potential. Apart from the valence anion , the uracil .(H2O)(3) complex can form a stable dipole-bound anion, b ut as the present calculations indicate the electron affinity, which c orresponds to this attachment, is very small (13 meV). The structure o f the dipole-bound anion is virtually identical with the structure of the neutral complex.