Structure and stability of neutral and cationic Al_nO clusters

In this paper various structural possibilities for Al_nO neutral and cationic isomers were investigated by using the B3LYP/6-311G(3df) method. Calculations of this paper predicted the existence of a number of previously unknown isomers. The stabilities of the Al_nO (n=2-7) clusters with even n are greater than those with odd n, however the stabilities of cationic ions have the opposite odd--even alternation. The mass spectra observations of Al₁₇O⁺ and Al₁₉O⁺ ions support our theoretical predictions on their stabilities.