Vibrational calculations for the H2O … CO complex

The H2O–CO complex was studied with DFT calculations. The complex has two stable structures, H2O–CO and H2O–OC, and their BSSE-corrected interaction energies at the CR-CC(2,3)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ level of theory are −8.43 and −3.38 kJ mol−1. The vibrational properties of the complexes were studied via harmonic and anharmonic calculations. The harmonic calculations are able to give a qualitative view on the complexes whereas the anharmonic CC-VSCF calculations are able to place the vibrational transitions close to their experimentally determined positions. The anharmonic calculations also indicate that both complex structures have a rich overtone and combination spectra.