Born–Oppenheimer DFT molecular dynamics studies of S2O2: Non-harmonic effects on the lowest energy isomers

Born–Oppenheimer DFT molecular dynamics (BO-DFT-MD) simulations were performed on the three lowest energy isomers of S2O2. After a careful calibration of the electronic structure method, the calculations were done using the B3PW91/aug-cc-pVTZ method. The dynamic vibrational spectra are reported and the lowest vibrational modes are identified, which correlate well with ab initio static predictions. The non-harmonic effects are non-negligible for the studied isomers. The largest non-harmonic contributions (up to 22%) were found for the third and fourth modes of the cis-OSSO C2v isomer. The relative vibrational peak intensities provide valuable information for the identification of this as yet undetected stable species.