A density functional
theory +
U
systematic theoretical
study was performed on the geometry, electronic structure, and energies
of properties relevant for the chemical reactivity of TiO
2
anatase. The effects of D3(BJ) dispersion correction and the Hubbard
U
value over the energies corresponding to the TiO
2
/Ti
2
O
3
reduction reaction, the oxygen vacancy
formation, and transition-metal doping were analyzed to attain an
accurate and well-balanced description of these properties. It is
suggested to fit the Hubbard correction for the metal dopant atom
by taking as reference the observed low spin–high spin (HS)
energy difference for the metal atom. PBEsol-D3 calculations revealed
a distinct electronic ground state for the yttrium-doped TiO
2
anatase surface depending upon the type of doping and interstitial
or substitutional defects. Based on the calculations, it was found
that a HS state explains the observed ferromagnetism in cobalt-substituted
TiO
2
anatase. The results presented herein might be relevant
for further catalytic studies on TiO
2
anatase using a large
surface model that would be worthwhile for heterogeneous catalysis
simulations.