Pinwheel binding of hydrogen molecules to acetylene

Ab initio and model potential calculations have been performed to investigate the interaction between hydrogen molecules and acetylene. The hydrogen–acetylene dimer has a T-shaped structure. Additional hydrogen molecules prefer the same arrangement with respect to the acetylene and, in successive steps, form a pinwheel structure with up to six hydrogen molecules pointing outward from the carbon–carbon triple bond of acetylene. Ground vibrational state calculations done with a model potential have been performed to make predictions of the zero-point energies of the small clusters and to understand the nature of the interactions leading to the pinwheel (H2)6–HCCH cluster.