Abstract: | Ab initio STO -3G geometries and relative energies for uracil (U) and the tautomer 4-hydroxyuracil (U*) were obtained with the HONDO program utilizing the rapidly convergent method of Murtaugh and Sargent for geometry optimization. ΔE for U?U* is 6.61 kcal/mole. The reaction field continuum model for solvent effect indicates a preferential stabilization of U* by 1.0 kcal/mole. The calculated gas phase Kt and solution Kt for U?U* are 1.44×10?5 and 1.3×10?4, respectively. |