Ab initio molecular dynamics studies on the ground singlet potential energy surface of the tetraoxygen molecule, O4

We study the finite temperature dynamical process followed by the D2d singlet ground state of tetraoxygen, O4. Born–Oppenheimer ab initio molecular dynamics (AIMD) simulations are done at near-room temperature and at 700 K using a calibrated DFT-based electronic structure description. The vibrational spectra are reported and the lowest vibrational modes are identified, which correlate well with ab initio static predictions. The largest non-harmonic contributions on the spectra are found for the modes involving ν5(B1) and ν6(A1) quanta. The relative vibrational peak intensities provide valuable information for the identification of this as yet undetected stable polyoxygen species.