MOLECULAR-DYNAMICS CALCULATION OF THE INFRARED-SPECTRA IN LIQUID H2O-D2O MIXTURES

The frequency distributions corresponding to the vibrational and libra tional molecular motions in liquid water and isotopically substituted mixtures are investigated. The infrared spectra is calculated from mol ecular dynamics simulations assuming a flexible single point charge (S PC) potential. A new set of parameters for the intramolecular potentia l which allows a reliable reproduction of the peaks of the experimenta l infrared spectra in the gas and liquid phases is proposed. Pure H2O, D2O and HDO liquids as well as dilute HDO solutions are analyzed. It has been verified that the OH and OD stretching modes in HDO are very close to those in H2O and D2O and that the HDO spectra is little influ enced by different environments (HDO, H2O and D2O).