Implementation of techniques for computing optical properties in 0-3 dimensions, including a real-space cutoff, in ABINIT

We have implemented the calculation of optical matrix elements with and without the inclusion of a real-space cutoff in the open-source software package ABINIT. We have also included the possibility to add the contribution arising from the non-local term of the pseudopotential operator. The implementation has been tested successfully for atoms, bulk silicon, and an oxidized silicon surface.