Linear scaling approach for atomistic calculation of excitonic properties of 10-million-atom nanostructures

Numerical calculations of excitonic properties of novel nanostructures, such as nanowire and crystal phase quantum dots, must combine atomistic accuracy with an approachable computational complexity. The key difficulty comes from the fact that excitonic spectra details arise from atomic-scale contributions that must be integrated over a large spatial domain containing a million and more atoms. In this work we present a step-by-step solution to this problem: a combined empirical tight-binding and configuration interaction scheme that unites linearly scaling computational time with the essentials of the atomistic modeling. We benchmark our method on the example of well-studied self-assembled InAs/GaAs quantum dots. Next, we apply our atomistic approach to crystal phase quantum dots containing more than 10 million atoms.