A Shell Model for Atomistic Simulation of Charge Transfer in Titania

Journal Article · Thu May 22 04:00:00 EDT 2008 · Journal of Physical Chemistry C, 112(20):7678-7688

DOI:https://doi.org/10.1021/jp8007865· OSTI ID:937030

Kerisit, Sebastien N; Deskins, N Aaron; Rosso, Kevin M; Dupuis, Michel

The derivation of atomistic potential parameters, based on electronic structure calculations, for modeling electron and hole polarons in titania polymorphs is presented. The potential model is a polarizable version of the Matsui and Akaogi model (Matsui, M.; Akaogi, M. Mol. Simul. 1991, 6, 239) that makes use of a shell model to account for the polarizability of oxygen ions. The -1 and +1 formal charges of the electron and hole polarons, respectively, are modeled by delocalizing the polaron’s charge over a titanium or oxygen ion, respectively, and its first nearest-neighbors. The charge distributions and the oxygen polarizability were fitted to the reorganization energies of a series of electron and hole polaron transfers in rutile and anatase obtained from electronic structure calculations at zero Kelvin and validated against lattice deformation due to both types of polaron. Good agreement was achieved for both properties. In addition, the potential model yields an accurate representation of a range of bulk properties of several TiO2 polymorphs as well as Ti2O3. The model thus derived enables us to consider systems large enough to investigate how the charge transfer properties at titania surfaces and interfaces differ from those in the bulk. For example, reorganization energies and free energies of charge transfer were computed as a function of depth below vacuum-terminated rutile (110) and anatase (001) surfaces using a two-state model based on Marcus theory. These calculations indicate that deviations from bulk values at the surface are substantial but limited to the first couple of surface atomic layers and that polarons are generally repelled from the surface. Moreover, attractive sub-surface sites may be found as is predicted for hole polarons at the rutile (110) surface. Finally, several charge transfers from under-coordinated surface sites were found to be in the so-called Marcus inverted-region.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 937030
• Report Number(s): PNNL-SA-58536; 3564a; KC0302010
• Journal Information: Journal of Physical Chemistry C, 112(20):7678-7688, Journal Name: Journal of Physical Chemistry C, 112(20):7678-7688 Journal Issue: 20 Vol. 112
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
CHARGE DISTRIBUTION
DEFORMATION
ELECTRONIC STRUCTURE
ELECTRONS
Environmental Molecular Sciences Laboratory
OXYGEN
OXYGEN IONS
POLARIZABILITY
POLARONS
RUTILE
SHELL MODELS
SIMULATION
TITANIUM
anatase(001)
charge transfer
molecular dynamics
rutile(110)
shell model
titania