Exploring rotation-translation coupling for a confined asymmetric rotor using molecular dynamics simulations: the case of the water molecule trapped inside a rare gas matrix

ABSTRACT

Differences between gas-phase and matrix-isolated rotational and rovibrational spectra of the water molecule are interpreted in term of the confined rotor model. The parameters of this model enable the isotopic composition of the molecule, which has non-trivial impacts on the spectra of matrix-isolated confined rotors, to be taken into account on a very simple and intuitive basis. We use molecular dynamics simulations to systematically explore the effects of the mass distribution of various isotopomers of the water molecule on the coupled rotational and translational dynamics of the confined asymmetric rotor, and on their coupling with the phonons of the argon matrix. Analysis of the trajectories reveals that, depending on the mass distribution, a preferred orientation of the water molecule can be strongly imposed by the topology of its interaction potential with the confinement medium. Features of the confining potential, and of the rotation-translation coupling, are thus revealed from classical molecular dynamics simulations.

KEYWORDS:

• Confinement
• matrix isolation spectroscopy
• rotation-translation coupling
• isotopic effects
• molecular dynamics simulations

Acknowledgments

The computational resources were provided by Calcul Québec and Compute Canada, through the financial support of the Canadian Foundation Innovation (CFI). This work was supported by the Université de Sherbrooke, the Fond Québécois de la Recherche sur la Nature et les Technologies (FRQNT) and the Natural Sciences and Engineering Research Council of Canada (NSERC).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Université de Sherbrooke, the Fond Québécois de la Recherche sur la Nature et les Technologies (FRQNT) and the Natural Sciences and Engineering Research Council of Canada (NSERC).