Intramolecular Dynamics of the Rovibrational Energy in a Carbonyl Sulfide Molecule

Abstract

We discuss the efect of low rotational excitations on intramolecular vibrational energy redistribution (IVR) in an isolated carbonyl sulfide (OCS) molecule in its electronic ground state. Computational experiments were performed to analyze the intramolecular rotational-vibrational energy redistribution (IRVR) and the intramolecular vibrational rotational energy transfer (IVRET). We use the MCTDH software to solve the Schrödinger equation for wave packets corresponding to initial excitations on vibrational local modes. The wave packets are prepared having the same initial vibrational excitations but differing in the total angular momentum. We found that IVR is affected by K-mixing due to Corio lis coupling and that centrifugal coupling does not have a relevant role on IVR. Moreover, rotational effects on IVR depends on the vibrational bending mode. If the bending mode is not excited, K-mixing is negligible. If it is excited, then K-mixing occurs in a signif icant degree and as a result the wave packet evolves onto a pseudodecoherent (steady) state. However, the net redistribution does not change, i.e., on average IVR behaves in the same way. Furthermore, loss of vibrational coherence happened even when IVRET is insignifcant, implying that analyzing the total vibrational energy is not fully conclusive to predict changes of IVR due to rotational excitations.