An intramolecular vibrationally excited intermolecular potential energy surface and predicted 2OH overtone spectroscopy of H 2 O-Kr.

A new five-dimensional potential energy surface (PES) for H 2 O-Kr which explicitly includes the intramolecular 2OH overtone state of the H 2 O monomer is presented. The intermolecular potential energies were evaluated using explicitly correlated coupled cluster theory [CCSD(T)-F12] with a large basis set. Four vibrationally averaged analytical intermolecular PESs for H 2 O-Kr with H 2 O molecules in its |00 + 〉, |02 + 〉, |02 - 〉, and |11 + 〉 states are obtained by fitting to the multi-dimensional Morse/Long-Range potential function form. Each vibrationally averaged PES fitted to 578 points has root-mean-square (RMS) deviations smaller than 0.14 cm -1 and requires only 58 parameters. The combined radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm were employed to calculate the rovibrational energy levels for |00 + 〉, |02 + 〉, |02 - 〉, and |11 + 〉 states of the H 2 O-Kr complexes. The calculated |02 - 〉Π f/e (1 01 ) ← |00 + 〉Σ e (0 00 ) and |02 + 〉Π f/e (1 10 ) ← |00 + 〉Σ e (1 01 ) infrared transitions are in excellent agreement with the experimental values with RMS discrepancies being only 0.007 and 0.016 cm -1 , respectively. These analytical PESs can be used to provide reliable theoretical guidance for future infrared overtone spectroscopy of H 2 O-Kr.