| Autor: |
Sruthil Lal, S. B., Sharan, A., Devaraj, M., Posselt, M., Sasikala Devi, A. A. |
| Jazyk: |
angličtina |
| Rok vydání: |
2021 |
| Předmět: |
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| Zdroj: |
arXiv:2112.03027 [cond-mat.mtrl-sci]: http://arxiv.org/abs/2112.03027 |
| Popis: |
The quasiparticle electronic structure and optical excitation of anatase TiO2 is determined within the framework of many-body perturbation theory (MBPT) by combining the G0W0 method and the Bethe-Salpeter Equation (BSE). A modified version of the HSE06 screened hybrid functional, that includes 20% exact Fock exchange (HSE06(20)) as opposed to 25% in the standard HSE06 functional, is used to set up the starting Hamiltonian for G0W0+BSE calculations. The HSE06(20) functional accurately predicts the ground state electronic band structure. BSE calculations based on data from G0W0+HSE06(20) yield direct optical excitation energies and oscillator strengths in excellent agreement with existing experiments and theoretical calculations characterizing direct excitation. In particular, an exciton binding energy of 229 +- 10 meV is obtained, in close agreement with experiments. The projections of excitonic states onto the quasiparticle band structure in a fatband representation shows that the lowest optical transition of anatase TiO2 consists of excitons originating from the mixing of direct transitions within band pairs running parallel to the Gamma-Z direction in the tetragonal Brillouin zone. This implies a strong spatial localization of excitons in the xy plane of the lattice. This investigation highlights the importance of a suitable non-interacting Hamiltonian for the MBPT based quasiparticle G0W0 and subsequent BSE calculations and suggests HSE06(20) as an optimal choice in the case of anatase TiO2. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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