A theoretical study on the stability of N15+ cluster

Abstract

Ab initio (MP2) and density functional theory (DFT) methods have been used to examine three isomers of the N₁₅⁺ cluster with the 6-31G* basis set. The most stable isomer is the trans structure (C_S), containing one aromatic N₅ ring and two N₅ side chains. The decomposition pathways of the three isomers were studied at the B3LYP/6-31G* level of theory. Relative energies were refined at the level of B3LYP/6-311G(3df,2p)//B3LYP/6-31G* + ZPE (B3LYP/6-31G*). The decomposition reactions of the global minimum prefer side-chain fission, with barriers of 9.3 and 12.0 kcal mol⁻¹ for N₂ and N₅⁺ (C_2v) fission reactions, respectively. The ring breaking reaction has a barrier of 19.4 kcal mol⁻¹. The corresponding side-chain fission barriers for the second structure (C_2v), which is a cis isomer, are predicted to be 9.3 kcal mol⁻¹ and 12.1 kcal mol⁻¹, respectively. The barrier height for breaking the center ring of the three connected N₅ rings of the third structure (C₂) is predicted to be 8.0 kcal mol⁻¹.