[Vibrational spectra of thymine calculated from DFT and their comparison with experimental results]

The vibrational spectra of thymine were predicted by density functional theory (DFT). In the calculation B3LYP complex function, and diffuse function and polarization function were added to heavy atoms and light atoms. Taking the effects of H-bonds into consideration, the authors added two water molecules in our calculation and simulated the case of forming H-bonds in crystal thymine. Whilst the Raman and infrared spectra of thymine were recorded, and the spectra of thymine calculated from DFT agree with the experimental results. The calculation results in the present paper are more approximate to the experimental data than ever reported. The vibrational modes of thymine were assigned.