Structure and stability of AlC2N isomers: A comparative ab initio and DFT study

A theoretical study of the different AlC2N isomers has been carried out. Th e global minimum is predicted to be a linear AlCCN isomer, whereas the prev iously predicted ground state, a three-membered ring isomer: lies much high er in energy (more than 25 kcal/mol at the more reliable levels of theory). We have found four other structures lying lower in energy than the three-m embered ring, two of them being rhombic structures. The preferred atomic ar rangement for linear geometries, as in the case of its analogue BC2N system , is AlCCN. However, contrary to what is observed for BC2N, the global mini mum is a (3)Sigma state. Predictions for the vibrational frequencies, rotat ional constant, and dipole moment, as well as for the atomization energy an d dissociation into Al + CCN, have been made for the global minimum. On the basis of these results we may conclude that the ground state of AlC2N is r elatively stable and therefore it might be of interest for experimentalists .