MOLECULAR-DYNAMICS SIMULATIONS WITH A FLEXIBLE AND POLARIZABLE POTENTIAL - DENSITY OF STATES FOR LIQUID WATER AT DIFFERENT TEMPERATURES

Molecular dynamic simulations for liquid H2O and D2O are reported in the temperature range 238-368 K. We have used the NCC-vib interaction potential, which is obtained from ab initio data, allows vibrations and includes explicitly polarizability. We report on the translational and rotational velocity autocorrelation functions and on the density of states in the range 0-4500 cm-1. Special attention is given to the computation of the translational, librational, bending, stretching and overtones spectra comparing liquid H2O with D2O, temperature dependences, and the positions of the simulated spectra with those from infrared, Raman and neutron scattering experiments. The overall agreement is satisfactory; minor discrepancies in the bending and stretching frequency positions have suggested improvements for the interaction potential.