Bending relaxation of H$_2$O by collision with para- and ortho-H$_2$

Ricardo Manuel Garcia-Vazquez; Alexandre Faure; Thierry Stoecklin

paper

Bending relaxation of H $_{2}$ O by collision with para- and ortho-H $_{2}$

arXiv:2311.08956

Abstract

We extend our recent theoretical work on the bending relaxation of H $_{2}$ O in collisions with H $_{2}$ by including the three water modes of vibration coupled with rotation, as well as the rotation of H $_{2}$ . Our full quantum close-coupling method (excluding the H $_{2}$ vibration) is combined with a high-accuracy nine-dimensional potential energy surface. The collisions of para-H $_{2}$ O and ortho-H $_{2}$ O with the two spin modifications of H $_{2}$ are considered and compared for several initial states of H $_{2}$ O. The convergence of the results as a function of the size of the rotational basis set of the two colliders is discussed. In particular, near-resonant energy transfer between H $_{2}$ O and H $_{2}$ is found to control the vibrational relaxation process, with a dominant contribution of transitions with delta j2 = +2, +4. Finally, the calculated value of the H $_{2}$ O bending relaxation rate coefficient at 295 K is found to be in excellent agreement with its experimental estimate.

Bending relaxation of H2​O by collision with para- and ortho-H2​

Abstract

Bending relaxation of H $_{2}$ O by collision with para- and ortho-H $_{2}$