Theoretical study on the structures and dissociation processes of hexatomic sulphur

Using B3PW91/6-31+G(3d) method based on the density functional theory (DFT) we have investigated the potential energy hypersurface (PES) of hexasulphur (S6). Eight stable isomeric structures are located and connected by eight transition states on the PES. Compared with previous theoretical results, the results of our method are in better agreement with the experimental ones. Especially, we have also studied two possible dissociation channels of S6 based on the rule of bond breaking in unimolecular reaction [R.G. Pearson, Symmetry Rules for Chemical Reaction, Orbital Topology and Elementary Processes, A Wiley-Interscience Publication, 1976]. One is from the chair-shaped structure to 2S3 through a transition state and the other is that the prism-shaped isomer dissociate to 3S2 directly.