Geometries of Mg_xAl_yN (x,y=1-5) clusters are studied by using hybrid density functional theory (B3LYP) with 6-311+G^* basis sets. For lowest-energy structures of Mg_xAl_yN clusters, stabilities and electronic properties are investigated. It shows that planar structures are dominant structures of Mg_xAl_yN (x+y≤4) clusters. The lowest-lying Mg_xAl_yN clusters mostly derived from ground-state structures of Al_nN or Mg_x-1Al_y+1N clusters. Mg_xAl_yN clusters are stable with respect to fragmentation into atoms or smaller clusters. Compared with neighboring clusters, MgAl₃N and Mg₃Al₃N clusters own higher stability. For all Mg_xAl_yN clusters studied, we found co-existence of covalent, ionic, and metallic bonding characteristics. Furthermore, ionization potential and electron affinity exhibit weak oscillations as increasing cluster size. Ro general pattern is observed.

Energy level intervals, QED contributions and transition probabilities of magnetic dipole (M1) and electronic dipole (E1) for 1s²3s²S_1/2→1s²2s²S_1/2,and 1s²2p²P_1/2→1s²2s²S_1/2 transitions are calculated for the Li-like ions (Z=3~100) using the fully relativistic multiconfiguration Dirac-Fock method with Breit and QED correction. Comparisons between the M1 and E1 transitions are made.