The structures of (MgO)(3n) (2or=6 (except 7) the rocksaltlike structure is favored, which is the same as that of the bulk. The n=7 is an interesting case, where the structure again is the hexagonal tube as the most stable structure. However, from the second order difference of the average atomization energy, we find that the n=7 case is thermodynamically unstable with respect to disproportionation to the smaller and larger clusters. The result may be the reason that it is not observed in the experiment. Therefore, we can conclude that the geometry transition really takes place at n=6. The rocksalt is the most stable structure for a large range of n numbers, from the (MgO)(3x6) cluster to bulk magnesium oxide. The result is different from Wilson's previous prediction because of the use of the ionic potential.

The size-dependent electronic, structural and magnetic properties of AgnFe (n ⩽ 15) clusters have been investigated by using the density functional theory (DFT) within the generalized gradient approximation. The starting structures were generated from empirical genetic algorithm simulations. The most stable structures were then selected from a number of structural isomers based on the results of the further DFT calculations. The atom prefers to stay at the centre of the clusters. The 2D to 3D transition occurs at n = 6. The magnetic properties and the geometric structures are strongly correlated. For , the total magnetic moment of the cluster is quenched. The reason is similar to the Kondo effect in bulk metal. Also, is considered to be very stable according to the 18-electron counting rule.

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