Theoretical emission spectra of HNC() on a new ab initio potential energy surface

We report a new ab initio potential energy surface of the excited ( A ˜ 1 A ″ ) state of HCN/HNC and the transition dipole function to the ground ( X ˜ 1 A ′ ) state at the MRCI/aug-cc-pVTZ level of theory. Resonance emission spectra from several low-lying and predissociative vibrational states of the HNC( A ˜ 1 A ″ ) isomer are calculated, which show the dominance of the C–N progressions, due apparently to the large difference in the equilibrium C–N bond lengths in the two electronic states.