Theoretical study of structures and stabilities of CmN2 (m=1-14) ions

Geometrical and electronic properties of CmN2 (m=1-14) positively and negatively charged clusters have been investigated by hybrid B3LYP functional at the respective 6-311G(d) and 6-311+G(d) levels. Our results revealed that CmN2 (m=2-14) cationic ions and CmN2 (m=6-14) anions form linear conformer with D[infinity]h symmetry except for C11N2+ cationic ion whereas CmN2 (m=1-5) anions form chain-like arrangements. Two N atoms favor to bond at ends in linear and chain-like configurations. Both calculated HOMO-LUMO gaps and adiabatic ionization potentials showed that the CmN2 (m=1-14) clusters with even m are more stable than those with odd m. The second difference in energy for CmN2+ (m=1-14) ions revealed that the cationic ions with even m are more stable than those with odd m, which is consistent with the observed cationic even-odd alternation of the TOF signal intensities. The relative stability of anions is in opposition to that of cationic clusters.