Evolution of structure, stability, and nonlinear optical properties of the heterodinuclear CNLin (n=1-10) clusters.

The lowest-energy structures and stabilities of the heterodinuclear clusters, CNLin (n=1-10) and relevant CNLin(+) (n=1-10) cations, are studied using the density functional theory with the 6-311+G(3df) basis set. The CNLi6 and CNLi5(+) clusters are the first three-dimensional ones in the CNLin(0/+) series, respectively, and the CN group always caps the Lin(0/+) moiety in the CNLin(0/+) (n=1-9) configurations. The CN triple bond is found to be completely cleaved in the CNLi10(0/+) clusters where the C and N atoms are bridged by two Li atoms. The CNLin (n=2-10) clusters are hyperlithiated molecules with delocalized valence electrons and consequently possess low VIP values of 3.780-5.674eV. Especially, the CNLi8 and CNLi10 molecules exhibit lower VIPs than that of Cs atom and can be regarded as heterobinuclear superalkali species. Furthermore, these two superalkali clusters show extraordinarily large first hyperpolarizabilities of 19,423 and 42,658au, respectively. For the CNLin(+) cationic species, the evolution of the energetic and electronic properties with the cluster size shows a special stability for CNLi2(+).