Abstract
Hydrogen sulfide () and hydrogen () crystallize into a ‘guest-host’ structure at 3.5 GPa and, at the initial formation pressure, the rotationally disordered component molecules exhibit weak van der Waals-type interactions. With increasing pressure, hydrogen bonding develops and strengthens between neighboring molecules, reflected in a pronounced drop in S-H vibrational stretching frequency and also observed in first-principles calculations. At 17 GPa, an ordering process occurs where molecules orient themselves to maximize hydrogen bonding and molecules simultaneously occupy a chemically distinct lattice site. Intermolecular forces in the system may be tuned with pressure from the weak hydrogen-bonding limit to the ordered hydrogen-bonding regime, resulting in a novel clathrate structure stabilized by cooperative interactions.
- Received 5 July 2011
DOI:https://doi.org/10.1103/PhysRevLett.107.255503
© 2011 American Physical Society