The structures and electronic states of zinc–water clusters Znn(H2O)m (n = 1–32 and m = 1–3)

Abstract

Ab initio and Density Functional Theory (DFT) calculations have been carried out for zinc–water clusters Zn_n–(H₂O)_m (n = 1–32 and m = 1–3, where n and m are the numbers of zinc atoms and water molecules, respectively) to elucidate the structure and electronic states of the clusters and the interaction of zinc cluster with water molecules. The binding energies of H₂O to zinc clusters were small at n = 2–3 (2.3–4.2 kcal mol⁻¹), whereas the energy increased significantly in n = 4 (9.0 kcal mol⁻¹). Also, the binding nature of H₂O was changed at n = 4. The cluster size dependency of the binding energy of H₂O accorded well with that of the natural population of electrons in the 4p orbital of the zinc atom. In the larger clusters (n > 20), it was found that the zinc atoms in surface regions of the zinc cluster have a positive charge, whereas those in the interior region have a negative charge with the large electron population in the 4p orbital. The interaction of H₂O with the zinc clusters were discussed on the basis of the theoretical results.