title: Structural and electronic properties of photoexcited TiO2 nanoparticles from first principles.
abstract: The structure and energetics of excitons and individual electron and hole polarons in a model anatase TiO2 nanoparticle (NP) are investigated by means of Density Functional Theory (DFT) and Time Dependent (TD)-DFT calculations. The effect of the Hartree-Fock exchange (HF-exc) contribution in the description of TiO2 NPs with unpaired electrons is examined by comparing the results from semilocal and hybrid DFT functionals with different HF-exc percentages, including a long-range corrected hybrid functional. The performances of TD-DFT and ground state (SCF) DFT approaches in the description of the photoexcited polaron states in TiO2 NPs are also analyzed. Our results confirm that the HF-exc contribution is essential to properly describe the self-trapping of the charge carriers. They also suggest that long-range corrected functionals are needed to properly describe excited state relaxation in TiO2 NPs. TD-DFT geometry optimization of the lowest excited singlet and triplet states deliver photoluminescence values in close agreement with the experimental data.
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM, via Elce di Sotto 8, I-06123 Perugia, Perugia, Italy.|Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , via Elce di Sotto 8, I-06123 Perugia, Perugia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nunzi
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM, via Elce di Sotto 8, I-06123 Perugia, Perugia, Italy.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Agrawal
authors.affiliation: Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Annabella
authors.initials: A
authors.lastname: Selloni
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM, via Elce di Sotto 8, I-06123 Perugia, Perugia, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: De Angelis
mesh_terms: D004583:Electrons; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D055668:Photochemical Processes; D011789:Quantum Theory; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium