  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 atomicscale contributions
that must be integrated over a large spatial domain containing a million and
more of atoms. In this work we present a step-by-step solution to this problem:
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 wellstudied self-assembled
InAs/GaAs quantum dot. Next, we apply our atomistic approach to crystal phase
quantum dots containing more than 10 million atoms.
