Ab initio and model investigation of acetylene clustering around hydrogen cyanide

Ab initio calculations have been performed to determine the structures and interaction energetics of (HCCH)2–HCN and certain related clusters. The clusters have arrangements of each HCN–HCCH pair being essentially either T-shaped, with the HCN as a proton donor, or linear, with the acetylene as the proton donor to the nitrogen end of HCN. Three-body energetic features are small as are the polarization energy effects. A model potential has been applied to these and larger clusters. Though strongly polar, substitution of one HCN for acetylene in a pure cluster yields small structural differences.