An accurate full-dimensional permutationally invariant potential energy surface for the interaction between H 2 O and CO

• Published in: Physical chemistry chemical physics : PCCP Vol. 21; no. 43; pp. 24101 - 24111
• Main Authors: Liu, Yang, Li, Jun
• Format: Journal Article
• Language: English
• Published: 07.11.2019
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/C9CP04405A

The interaction between H 2 O and CO has been the subject of numerous experimental and theoretical investigations for a long time due to their important roles in various environments, such as the atmosphere, combustion of hydrocarbons, and the interstellar medium. In this work, the first full-dimensional accurate potential energy surface (PES) was developed for the CO + H 2 O system based on ca. 102 000 points calculated at the level of an explicitly correlated coupled-cluster method with single, double, and perturbative triple excitations with the augmented correlation-consistent polarized triple zeta basis set (CCSD(T)-F12a/AVTZ) using the permutation invariant polynomial-neural network (PIP-NN) method. The geometries, energies, and frequencies of the two complex wells, CO–H 2 O and OC–H 2 O, and one transition state connecting them, as well as some interconversions between different conformers, are accurately reproduced by the PES, thanks to the small fitting error of only 1.08 meV. With full-dimensional degrees of freedom considered in the PES, we found that there exist strong dependences of the CO and OH bond lengths on the OC–H 2 O and CO–H 2 O interaction energies, which is not possible in reduced dimensional PESs. Finally, classical dynamics was carried out to study the energy transfer between H 2 O and CO with different initial vibrational energies in H 2 O and different vibrational states in CO.