Fully quantal calculation of H-2 translation-rotation states in the (p-H-2)(2) @ 5(12)6(4) clathrate hydrate inclusion compound

摘要

The quantal translation-rotation (TR) states of the (p-H-2)(2) @ 5(12)6(4) clathrate hydrate inclusion compound have been computed. The ten-dimensional problem (in the rigid-cage and rigid-H-2 approximation) is solved by first approximating the H-2 moieties as spherically symmetric and solving for their 6D translational eigenstates. These are then combined with H-2 free rotational states in a product basis that is used to diagonalize the full TR hamiltonian. The computed low-energy eigenstates have translational components that are essentially identical to the 6D translational eigenstates and rotational components that are 99.9 composed of rotationally unexcited H-2 moieties. In other words, TR coupling is minimal for the low-energy states of the species. The low-energy level structure is found to be substantially more congested than that of the more tightly packed (p-H-2)(4) @ 5(12)6(4) clathrate species. The level structure is also shown to be understandable in terms of a model of (H2) 2 as a semirigid diatomic species consisting of two spherically symmetric H-2 pseudo-atoms. (C) 2014 AIP Publishing LLC.