The theoretical prediction of infrared spectra of trans- and cis- hydroxycarbene calculated using full dimensional ab initio potential energy and dipole moment surfaces
Accurate infra-red spectra of the two hydroxycarbene isomers are computed by diagonalizing the Watson Hamiltonian including up to four modes couplings using full dimensional potential energy and dipole moment surfaces calculated at the CCSD(T)/cc-pVTZ and CCSD/6-311G** levels, respectively. Anharmonic corrections are found to be very important for these elusive higher-energy isomers of formaldehyde. Both the energy levels and intensities of stretching fundamentals and all overtone transitions are strongly affected by anharmonic couplings between the modes. The results for trans-HCOH/HCOD are in excellent agreement with the recently reported IR spectra, which validates our predictions for the cis-isomers.