Theoretical study of Au_n clusters (n = 1-5) deposited on a rutile TiO₂ (110) slab, concerning structure and stability

The initial nucleation of gold clusters Au_n (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 2D→3D transition of small folding, from Au₃ →Au₄ , followed by an Au₄ →Au₅ transition of evident 3D character.