Molecular Structures and Energetics of the (TiO₂)_n (n = 1−4) Clusters and Their Anions

Abstract

The (TiO2)n clusters and their anions for n = 1-4 have been studied with coupled cluster theory [CCSD(T)] and density functional theory (DFT). For n > 1, numerous conformations are located for both the neutral and anionic clusters, and their relative energies are calculated at both the DFT and CCSD(T) levels. The CCSD(T) energies are extrapolated to the complete basis set limit for the monomer and dimer and calculated up to the triple-zeta level for the trimer and tetramer. The adiabatic and vertical electron detachment energies of the anionic clusters to the ground and first excited states of the neutral clusters are calculated at both levels and compared with the experimental results. The comparison allows for the definitive assignment of the ground-state structures of the anionic clusters. Anions of the dimer and tetramer are found to have very closely lying conformations within 2 kcal/mol at the CCSD(T) level, whereas that of the trimer does not. In addition, accurate clustering energies and heats of formation are calculated for the neutral clusters and compared with the available experimental data. Estimates of the titanium-oxygen bond energies show that they are stronger than the group VIB transition metal-oxygen bonds except for tungsten. The atomization energies of these clusters display much stronger basis set dependence than the clustering energies. This allows the calculation of more accurate heats of formation for larger clusters on the basis of calculated clustering energies.

MgH2 Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

“…There is a considerable amount of literature on the global minima structures of TiO 2 clusters. 22,42,43,44,45 Furthermore, in order to check the rigorousness of this approach we also considered candidate structures derived from different materials, namely SiO 2 , 46 and MgF 2 . 47,48 In order to survey the potential energy surface, especially of the smaller nanostructures, we relaxed many (59 in total) candidate structures.…”

Single oxygen vacancies of (TiO2)35as a prototype reduced nanoparticle: implication for photocatalytic activity

“…Compared to TiO 2 bulk, NPs are composed of strained lattices, mixed phases or interfaces with several defects. 18 On the other hand, the isolated TiO 2 clusters, Ti n O 2n (n < 17), 10,[19][20][21] have been investigated to compare their structures and properties with those of the bulk phases. However, the structure of clusters composed of few atoms is substantially different from that of the TiO 2 bulk and the cluster size is too small to explain the experimental observation.…”

Ab-initio study of free standing TiO2 clusters: Stability and magnetism

“…22,23 Implementing first principle calculation, with main attention devoted to their stability study [(TiO 2 ) n , n ¼ 1-4] (Ref. 24) and for larger clusters the (TiO 2 ) n nanoparticles with n ¼ 10-16, an interesting oddeven oscillation in the structural features has been observed. 25 …”