The effect of water on infrared spectra of DNA

The effect of water on infrared (IR) spectra of DNA is studied by using first-principles calculations based on the hybrid density functional theory. Our calculations of frequencies of C = O stretching modes in DNA without water do not reproduce the IR spectra, whereas calculations for DNA surrounded by water reproduce the IR spectra well. We also find that the energy of adsorption of one water molecule around a C = O site is large (≅0.6 eV) owing to hydrogen bond formation. We therefore conclude that the effect of water plays an important role as regards IR spectra of DNA in a water solution.