Variational study on the vibrational level structure and IVR behavior of highly vibrationally excited S0 formaldehyde

We perform large scale converged variational vibrational calculations on S0 formaldehyde up to very high excess vibrational energies (Ev), Ev ∼ 17,000 cm−1, using our vibrational method, consisting of a specific search/selection/Lanczos iteration procedure. Using the same method we investigate the vibrational level structure and intramolecular vibrational redistribution (IVR) characteristics for various vibrational levels in this energy range in order to assess the onset of IVR.

Graphical abstractSpectrum and IVR dynamics of the CH stretch overtone level ν1 + 4ν5 at Ev = 13,321.8 cm−1.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We calculate the spectrum and IVR dynamics of very highly excited vibrational levels in S0 formaldehyde. ► We use a specific search/selection procedure for contraction of the huge primitive basis state space into a small and representative active space. ► We use Lanczos iteration for diagonalization of the Hamiltonian matrix.