Résumé
Gas hydrates are nanoporous crystalline solids composed of hydrogen-bonded watermolecules forming cages within which gaseous molecules are encapsulated. Sincetheir initial discovery, interest in gas hydrates has grown exponentially from being ofmere scientific curiosity to offering a potential new energy solution to the imminentenergy crisis [1]. Gas hydrates are considered to be pivotal terrestrial andextraterrestrial ingredients, as they make up a great part of the Earth's seafloorsediments and play a role in extraterrestrial planetary formation scenari [2]. Forexample, clathrate hydrates of methane are extensively studied in astrophysicsbecause they are suspected to be present on several planets, satellites and comets ofthe Solar System [3].However, the description of such encapsulated molecular systems is often far fromcomplete. Indeed, in such nanoscale confinement, the translational center-of-massmotions of the caged molecules are quantized and strongly coupled to the molecularrotations, which are quantized too. To interpret experimental data (like inelastic neutronscattering), theoretical tools are useful but we need to go beyond the simple harmonicapproximation as the guest molecule presents very large amplitude motions(translation and rotation) and its interaction with the nanoscale cavity can be far fromharmonic. A rigorous quantum treatment of the intricate coupled translation-rotationand/or vibration-translation-rotation (considering the molecular hydrogen stretchingmode) dynamics of the caged diatomic molecules is far from a routine task.In this contribution, I will present a review on our recent progress in the developmentof efficient/accurate computational methods for the rigorous quantum treatment of theintricate coupled translation-rotation dynamics of the molecular hydrogen in waterclathrates [4-7]. In particular, the efficiency of the computational method will highlightthe impact of the condensed-phase environment on the spectroscopy of the confinedmolecule. Moreover, the efficiency of our computational scheme allows us to directlyprobe the quality of the considered intermolecular potentials (ranging from semiempiricalto the most sophisticated ab initio potentials).Bibliography:[1] C. I. Ratcliffe, Energy fuels, 36 (2022)[2] B.K. Chastain et al., Planetary and Space Science, 55 (2009)[3] O. Mousis et al., Astrobiology, 15, 4 (2015)[4] A. Chen et al., J. Chem. Theory Comput., 18, 7 (2022)[5] D. Lauvergnat et al., J. Chem. Phys., 150 (2019)[6] D. Benoit et al., Faraday Discuss., 212, 533 (2018)[7] A. Powers et al., J. Chem. Phys., 148 (2018)