A combined approach of first-principles density-functional calculations and the systematic cluster-expansion scheme is presented. The dipole, quadrupole, and Coulomb matrix elements obtained from ab initio calculations are used as an input to the microscopic many-body theory of the excitonic optical response. To demonstrate the hybrid approach for a nontrivial semiconductor system, the near-bandgap excitonic optical absorption of rutile TiO2 is computed. Comparison with experiments yields strong evidence that the observed near-bandgap features are due to a dipole-forbidden but quadrupole-allowed 1s exciton state.
|Original language||English (US)|
|Journal||Journal of the Optical Society of America B: Optical Physics|
|State||Published - Jul 1 2016|
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Atomic and Molecular Physics, and Optics