Vibrational properties of thymine,uracil and their isotopomers

Density functional theory (DFT) calculations using the B3LYP/6‐311G(d,p) basis set of ten isotopomers of thymine and four isotopomers of uracil, including the natural abundance isotopomers, are reported. Comparison of the calculated wavenumber shifts upon hydrogen, carbon and nitrogen isotopic substitution with those from experimental Raman and infrared measurements show good agreement in both the direction and the magnitude of the shift. These results are contrasted to previously reported calculations and discussed in the context of assigning the normal modes of thymine and uracil. Copyright © 2007 John Wiley & Sons, Ltd.