A New Full-Dimensional Intermolecular Potential Energy Surface and Rovibrational Energies of the HO-H Complex.

HO-H is a prototypical five-atom van der Waals system, and the interaction between HO and H plays an important role in many physical and chemical environments. However, previous full-dimensional intermolecular potential energy surfaces (IPESs) cannot accurately describe the HO-H interaction in the repulsive or van der Waals minimum region. In this work, we constructed a full-dimensional IPES for the title system with a small root-mean-square error of 0.252 cm by using the permutation invariant polynomial neural network method. The calculations were performed by employing the explicitly corrected coupled cluster [CCSD(T)-F12a] method with the augmented correlation-consistent polarized valence quintuple-ζ basis set. Based on the newly developed IPES, the bound states of the HO-H complex were calculated within the rigid-rotor approximation. The transition frequencies and band origins agreed well with the experimental values [Weida, M. J.; Nesbitt, D. J. , 110, 156-167] with errors less than 0.1 cm for most transitions. Those results demonstrate the high accuracy of our new IPES, which would build a solid foundation for the collisional dynamics of HO-H at low temperatures.