The OH radical-H2O molecular interaction potential

Abstract

The OH radical is one of the most important oxidants in the atmosphere due to its high reactivity. The study of hydrogen-bonded complexes of OH with the water molecules is a topic of significant current interest. In this work, we present the development of a new analytical functional form for the interaction potential between the rigid OH radical and H 2 O molecules. To do this we fit a selected functional form to a set of high level ab initio data. Since there is a low-lying excited state for the H 2 O ∙ O H complex, the impact of the excited state on the chemical behavior of the OH radical can be very important. We perform a potential energy surface scan using the CCSD(T)/aug-cc-pVTZ level of electronic structure theory for both excited and ground states. To model the physics of the unpaired electron in the OH radical, we develop a tensor polarizability generalization of the Thole-type all-atom polarizable rigid potential for the OH radical, which effectively describes the interaction of OH with H 2 O for both ground and excited states. The stationary points of ( H 2 O ) n ∙ O H clusters were identified as a benchmark of the potential.