科研之友
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摘要
The most stable (Al16Ti)(n +/-) (n=0-3) ions were modeled and optimized using density functional theory combined with all-electron spin-polarized calculations. The geometries, stabilities, and electronic structures of the (Al16Ti)(n +/-) (n=0-3) ionic clusters, as well as the adsorption structures and adsorption energies of H2O molecules on the (Al16Ti)(n +/-) (n=0-3) ionic clusters, were studied. The results were compared with those obtained for pure (Al-17)(n +/-) (n=0-3) ionic clusters. The spatial distributions of the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals for the (Al16Ti)(n +/-) (n=0-3) ionic clusters showed that the free electrons tend to occupy Ti sites. And a few residual free electrons would occupy sites with large curvatures. An extensive structure search was performed to identify the low-energy conformations of (Al16TiH2O)(n +/-) (n=0-3) complexes. Based on the geometries of the studied adsorption complexes, it was found that the most stable structures were prone to oxygen-based adsorption onto Ti atom. (Al16TiH2O)(+) ion featured the shortest average O-H bond length, that was similar to 0.0003 nm longer than that observed in isolated H2O molecule. The O-H bond length increased with either increasing or decreasing number of the electrons. The studies implied that Ti dopant in Al ionic clusters improved the dissociation efficiency of H2O molecules. Furthermore, the doping effect played a more important role than the geometry effect in determining the electronic structures of the (Al16Ti)(n) ionic clusters and their interaction with H2O molecules.
