title: When Anatase Nanoparticles Become Bulklike: Properties of Realistic TiO2Nanoparticles in the 1-6 nm Size Range from All Electron Relativistic Density Functional Theory Based Calculations.
abstract: All electron relativistic density functional theory (DFT) based calculations using numerical atom-centered orbitals have been carried out to explore the relative stability, atomic, and electronic structure of a series of stoichiometric TiO2anatase nanoparticles explicitly containing up to 1365 atoms as a function of size and morphology. The nanoparticles under scrutiny exhibit octahedral or truncated octahedral structures and span the 1-6 nm diameter size range. Initial structures were obtained using the Wulff construction, thus exhibiting the most stable (101) and (001) anatase surfaces. Final structures were obtained from geometry optimization with full relaxation of all structural parameters using both generalized gradient approximation (GGA) and hybrid density functionals. Results show that, for nanoparticles of a similar size, octahedral and truncated octahedral morphologies have comparable energetic stabilities. The electronic structure properties exhibit a clear trend converging to the bulk values as the size of the nanoparticles increases but with a marked influence of the density functional employed. Our results suggest that electronic structure properties, and hence reactivity, for the largest anatase nanoparticles considered in this study will be similar to those exhibited by even larger mesoscale particles or by bulk systems. Finally, we present compelling evidence that anatase nanoparticles become effectively bulklike when reaching a size of ∼20 nm diameter.
authors.affiliation: Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona , C/Martí i Franquès 1, 08028 Barcelona, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Lamiel-Garcia
authors.affiliation: Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona , C/Martí i Franquès 1, 08028 Barcelona, Spain.|Department of Chemistry, Sungkyunkwan University , Suwon 16419, Korea.
authors.forename: Kyoung Chul
authors.initials: KC
authors.lastname: Ko
authors.affiliation: Department of Chemistry, Sungkyunkwan University , Suwon 16419, Korea.
authors.forename: Jin Yong
authors.identifier: http://orcid.org/0000-0003-0360-5059
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona , C/Martí i Franquès 1, 08028 Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain.
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Bromley
authors.affiliation: Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona , C/Martí i Franquès 1, 08028 Barcelona, Spain.
authors.forename: Francesc
authors.identifier: http://orcid.org/0000-0003-2104-6123
authors.initials: F
authors.lastname: Illas