Intermolecular potential energy surface and bound state calculations for the HF–N2O van der Waals complex

We present a four-dimensional intermolecular potential energy surface (PES) and bound state calculations of the HF–N 2 O complex. The PES is constructed at the CCSD(T)-F12a level with aug-cc-pVXZ (X = T, Q) basis sets and extrapolated to the complete basis set limit. The PES was characterized with two minima and five saddle points involving in the bent and linear isomers. The planar bent NNO···HF structure is the global minimum, while the linear ONN···HF structure is a nearly isoenergetic local minimum, which is only 1.85 cm −1 lower that of bent isomer in dissociation energy. Intermolecular vibrational states of both isomers are assigned via wavefunction analysis. Calculated results were compared to microwave spectra, yielding excellent agreement for the linear isomer (RMSE = 0.0014 cm −1 ) and satisfactory overall consistency for the bent isomer (RMSE = 0.0202 cm −1 ). This work establishes a reliable correlation between high-precision PES and experimental rovibrational structures of floppy hydrogen-bonded complexes.