Abstract:

A molecular model for the water/platinum interface which includes the surface corrugation of the metal and orientationally anisotropic water/metal interactions has been proposed recently. In the present work the effect of the metal surface on the single particle dynamics of the water is discussed on the basis of the power spectra of the translational, rotational, and vibrational modes. There is good qualitative, and in some cases quantitative, agreement between the maxima of the power spectra and the frequencies of the modes observed for water adsorbed on the platinum (100) surface at low temperature in vacuum. The discrepancy found for the water-metal stretching vibration can be traced back to a feature of the water-metal potential. Translational and rotational mobility is strongly reduced in the vicinity of the surface even at the high simulation temperature of 349 K. Dynamical properties are bulk-like and isotropic beyond the first two layers of molecules.