RESUMO
The initial nucleation of gold clusters Aun (n = 1-5) on TiO2 rutile (110) reduced surface is studied using density functional theory and a full-potential augmented-plane-wave method implemented in the WIEN2k code. The first two gold atoms remained tied to the surface with a bond length similar to those belonging to other well-known related materials, while the other gold atoms do not spread over the surface; they preferred to form a new layer. The occurrence of relativistic effects produced a preferential triangle geometry for Au3 and a combination of triangular units for Au4 and Au5 . The Au-Au average distance increased from n = 2 to n = 5, indicating an expansion with a tendency to the bond distance found in the bulk. We are reporting an early 2Dâ3D transition of small folding, from Au3 âAu4 , followed by an Au4 âAu5 transition of evident 3D character.
RESUMO
The two published lithium peroxide structures, both ascribed to the hexagonal P6 space group, were subjected to reinterpretation, and another more symmetric structure, now belonging to the P6(3)/mmc space group, was found. Detailed density-functional quantum mechanical calculations and crystal structure optimizations were carried out on both structures and the energetic arguments obtained therewith helped to rule out one of them.