H/D isotope effect between adsorbed water (H2O, D2O, and HDO) and H2O- and D2O-ice Ih(0 0 0 1) basal surfaces based on the combined plane wave and localized basis set method

Abstract

To understand detailed geometrical changes and electronic structures of the adsorbed water molecules (H2O, D2O, and HDO) and H2O- and D2O-ice Ih(0 0 0 1) basal surfaces induced by the H/D isotope effect, nuclear quantum effects of the proton and deuteron in the first-principles calculations should be considered. We applied our developed combined plane wave and localized basis set (CPLB) method, which can directly treat the electronic structures of the surface and the localized adsorbed region with the nuclear quantum effect, to analyze the H/D isotope effect of adsorbed water molecules on ice. We demonstrated the geometrical change in the adsorbed water and H2O-ice surface due to the H/D isotope effect because the hydrogen bonds involving D (D2O and HDO) were longer than those involving H. Hence, the adsorption energies of D2O and HDO molecules were smaller than those of H2O because of the geometrical changes induced by the H/D isotope effect. The H/D isotope effect led to weaker adsorption energy and longer hydrogen bonds on the D2O-ice surface than those on the H2O-ice surface. We successfully described the H/D isotope effect of water adsorption on the ice Ih(0 0 0 1) surface by directly considering the quantum effect of the proton and deuteron.