MOLECULAR-SURFACE STRUCTURE OF ICE(0001) - DYNAMICAL LOW-ENERGY-ELECTRON DIFFRACTION, TOTAL-ENERGY CALCULATIONS AND MOLECULAR-DYNAMICS SIMULATIONS

A structural study of the surface of an ultrathin ice film grown on a Pt(lll) substrate was performed using dynamical low-energy electron di ffraction (LEED) at 90 K, together with total-energy calculations and molecular dynamics (MD) simulations. This ice film exhibits the common hexagonal phase Ih and exposes the (0001) surface without reconstruct ion. The surface is terminated as a full-bilayer that maximizes the nu mber of surface hydrogen bonds as confirmed by our total-energy calcul ations. Both LEED and MD simulations End that the outermost water mole cules have enhanced vibrational amplitudes making them practically und etectable by LEED even at 90 K. MD simulations of the half-bilayer ter minated surface yield results inconsistent with the LEED findings, thu s excluding this model. (C) 1997 Elsevier Science B.V.