The geometrical and electronic properties of (n＝1～12, m＝1, 2) clusters have been investigated at the B3LYP/6-311＋＋G** level. The structural and bongding characteristics, frequency and charge transfers of these doped clusters have been discussed. The calculations show that the ground state of C_nAl^＋ clusters was linear or polyline structures with terminal aluminum atom, and an aluminum atom inserted to a C_n ring form a new ring structure or with an aluminum atom bonded to one side of a monocyclic C_n ring. With the increasing of n, the total average bond length of the species is close to 0.138 nm gradually. The ground state structure of clusters is linear or polyline (cis or trans) C_coreAl_shell structure, which be formed by the combination of the terminal C atoms of two smaller C_n/2Al^＋ fragments. The overall average bond length of this species tends to be the value of 0.141 nm with increasing cluster size. Through the energy analysis of the ground state, we have obtained the stability information of clusters.

Key words: cluster, ground state structure, density functional theory, stability