Adsorption of Na and Hg on the Ice(Ih) Surface: A Density-Functional Study

The adsorption of Na and Hg atoms on the ice(Ih) Surface has been studied using first principles density-functional calculations. Apart from the stoichiometric surface, a defective surface, created by removing a hydrogen atom from the Surface, is also investigated. The adsorption energy for both Na and Hg is low oil the stochiometric Surface. The calculated adsorption energies of Hg are qualitatively similar with different theoretical approaches, e.g., a generalized-gradient approximation (GGA) functional, a hybrid functional, and MP2. However, for Na, the GGA calculations reveal a favorable adsorption process, whereas the more accurate B3LYP and MP2 calculations favor the desorption of Na on the stoichiometric ice surface. The adsorption of Hg oil the defective Surface is stronger (double) than that of the stoichiometric surface. Na adsorbs very strongly oil the defect site by forming Na-O bonds. The structures and energetics of all possible adsorption sites of Na and Hg oil both the stoichiometric and defective surfaces are analyzed and discussed.