Ab initio potential energy surface for unimolecular reactions during thermal conversion of acetylene

Unimolecular reactions involved in the pyrolysis of acetylene have been studied using ab initio molecular orbital-self-consistent field (MO-SCF) methods. A multiconfiguration (MC-SCF) method has proved adequate to describe the reaction studied. In the case of acetylene -> vinylidene isomerization we also performed multireference double configuration interaction (MRDCI) calculations: we found that vinylidene is a real minimum on the surface and it could play an important role in other, more endothermic, reactions.