Computing Raman Spectra With Wavelets Using The BigDFT Code

We report the calculations of Raman spectra using the BigDFT code.

The normal modes of vibration (or phonons) and their associated energies were found by slightly displacing each atom of the system around their ground position (this was already part of the BigDFT suite). We then added the possibility of computing the Raman intensity of each normal mode via electronic polarizability tensor calculations (in practice, this only amounts to applying small electric fields to the system of interest). The Raman spectra thus obtained are compared to the literature. A further check of the quality of the normal modes thus found is done by computing vibrational polarizability tensors.

The main perspective of this work is to use the order N version of the BigDFT code (instead of the usual cubic scaling version used in this work) to perform similar computations on larger systems.