Ab initio study of the formation of molecular complexes between Cl2 and C2H2

Abstract

The intermolecular potential energy surface (PES) for the interaction between the Cl2 C2H2 molecules has been comprehensively investigated using ab initio methods, aiming to locate the possible stationary points. The calculations were performed with the double zeta plus double polarization (DZ2P), triple zeta plus polarization (TZP) and triple zeta plus double polarization (TZ2P) basis sets, including electron correlation at the second-order Moller-Plesset (MP2) level, and basis set superposition error correction. Six stationary points were located on the PES: a T-shaped form where one chlorine atom is attached to the acetylene triple bond (bπ–σ type), a parallel form, a slipped parallel form, a crossed form and an inclined and a symmetric inverse T-shaped forms, where the van der Waals bond is between one of the H atoms of the acetylene and the Cl–Cl bond. At the MP2/TZ2P//MP2/TZP level of calculation, only the T-shaped and the parallel forms are minimum energy structures, and their stabilization energie...