Coupled translation-rotation bound states of molecular hydrogen in clathrate hydrates from first principles
Résumé
The study of small/medium size molecules inside nanoscale cavities of diverse host material, e.g.,
clathrates hydrates, cryogenic fluids (or superfluids), fullerenes, carbon nanotubes and zeolites, has received
a great deal of attention over the past years due to their broad application domain (condensed matter physics,
nanomaterial sciences, geoscience, quantum chemistry, astrophysical and planetary sciences, biophysics, ...).
However the description of such systems is often far from complete. Indeed,
in such nanoscale confinement, the translational center-of-mass motions
of the caged molecules are quantized and strongly coupled to the
molecular rotations, which are quantized too.
To interpret experimental
data, theoretical tools are useful but we need to go beyond the simple harmonic
approximation as the guest molecule presents very large amplitude
motions (translation and rotation) and its interaction with the nanoscale
cavity can be far from harmonic. A rigorous quantum treatment of the intricate
coupled translation-rotation (TR) dynamics of the caged diatomic
molecules is far from a routine task.