A cluster model of liquid water and its IR spectroscopic response

IR spectra of liquid water were modeled for a cluster of 214 molecules, using combined MD and ab initio DFT-BPW91/6-31G** computations. The model reproduced well the experimental absorption profile in the range of 0–4000 cm−1, positions, bandwidths and magnitudes of the absorption maxima for the OH stretching, bending and molecular librational modes. A band corresponding to the transitional motion is reproduced with a bigger error. The procedure can be applied universally and was also used for simulation of absorption spectra of liquid methanol.