  Atomic and electronic structures of TiO_2(110) surface with possible
adsorptional, substitutional and interstitial Au or Pt elemental impurities at
full and one-sixth monolayer concentrations were investigated by density
functional theory calculations using the projector augmented wave approach
within the plane wave method. Relative thermodynamic stabilities of such phases
have been discussed by means of their surface free energies. Our results
suggest that tunable photocatalytic activity can be achieved on Pt atom admixed
rutile (110) surface at low coverages.
