pyHRSOA and pyTHSOA: Postprocessing Codes for the Computation of Second and Third-Order Scattering Optical Activities

We present pyHRSOA and pyTHSOA, two postprocessing Python codes for the computation of the circular differential scattering ratio, a dimensionless quantity which is the central observable for two novel and promising nonlinear chiroptical techniques: the hyper-Rayleigh scattering optical activity (HRS-OA) and the third-harmonic scattering optical activity (THS-OA) spectroscopies. From a computational point of view, the simulation of the HRS-OA (THS-OA) spectroscopy requires the calculations of five first (second) hyperpolarizabilities and these can be obtained from quadratic (cubic) responses functions by using the DALTON quantum chemistry software. However, the expressions for the chiral and achiral contributions to the scattered intensities are quite complicated because these contain a lot of terms. In particular, for HRS-OA and THS-OA 30 and 46 molecular invariants need to be computed, thus complicating their computational implementation. The postprocessing codes presented here can be used as black-box tools for the simulations of HRS-OA and THS-OA spectroscopies. The source codes are available at https://gitlab.unamur.be/abonvici/pyhrsoa_pythsoa (DOI 10.5281/zenodo.15424494).