Abstract
Considerable work has gone into identifying and delineating the effects of quantum monodromy on molecules. Recently this included consideration of transition intensities of the NCNCS molecule using ab initio electric dipole moment functions in the Generalised SemiRigid Bender (GSRB) model [M. Winnewisser et al. PCCP 16, 17373-17407 (2014)]. In that work a discrepancy between the observed and calculated spectra was discovered. The purpose of the present work is to identify the source of that discrepancy - is it due to the physics of monodromy itself or are other issues involved? To investigate this we use the same theoretical approach for the simpler molecule HOCl. This allows us to identify a programming error affecting the b-type rovibrational transitions. We show that the NCNCS spectrum calculated with the corrected GSRB model does reproduce the experimental spectrum for pure rotational transitions within the ν7 large amplitude bending vibrational states, starting from the ground state and progressing through levels at the monodromy energy and beyond, while also reproducing the a-type υ:1←0rovibrational spectrum. However, the discrepancy with regard to the b-type rovibrational transitions remains. We discuss possible reasons for this discrepancy. In the course of this work we obtain a good GSRB model for the bending vibration-rotation levels of the atmospherically important HOCl molecule and its isotopologues. With ab initio calculations of the electric dipole moment function the GSRB calculates the rotation and bending rovibrational spectrum of HOCl in agreement with other determinations and with experiment. Using the physically constrained GSRB model, errors in tabulated transitions (including in the HITRAN database) were easily identified.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call