  Here we describe an efficient numerical implementation of the Bethe-Salpeter
equation to obtain the excitonic spectrum of semiconductors. This is done on
the electronic structure calculated either at the simplest tight-binding level
or through density funcional theory calculations based on local orbitals. We
use a simplified model for the electron-electron interactions which considers
atomic orbitals as point-like orbitals and a phenomenological screening. The
optical conductivity can then be optionally computed within the Kubo formalism.
Our results for paradigmatic two-dimensional materials such as hBN and MoS2,
when compared with those of more sophisticated first-principles methods, are
excellent and envision a practical use of our implementation beyond the
computational limitations of such methods.
