The defect formation energies and magnetic properties of Mg-V-Z (Z = Al, Ga, In) are systematically investigated by the method of first-principles calculations. The Z atom plays an important role in cube structural stability. The substitutions (exchanges) between second neighbor atoms are energetically favorable than that between first neighbor atoms. The Mg-rich V-poor, V-rich Mg-poor and V-rich In-poor alloys tend to form direct antisite defect, while the other off-stoichiometry alloys tend to form indirect antisite defects. The indirect antisite defect pairs consisting of Mg_V and V_Mg1 are the easiest to form in stoichiometric alloys. The magnetic moments of V atoms at defect sites are antiparallel to and smaller than those at normal sites. The magnetic moments of V at normal sites are sensitive to the distances between themselves and defect atoms.

用第一性原理计算系统地研究了Mg-VZ（Z = Al，Ga，In）的缺陷形成能和磁性能。Z原子在立方体结构稳定性中起重要作用。第二相邻原子之间的取代（交换）在能量上比第一相邻原子之间的取代（交换）在能量上有利。富镁贫V，富镁贫V和富钒贫In的合金倾向于形成直接的反位缺陷，而其他化学计量比低的合金则倾向于形成间接的反位缺陷。由Mg _V和V _Mg1组成的间接抗位缺陷对是化学计量合金中最容易形成的。缺陷部位的V原子的磁矩与正常部位的磁矩反平行且小于其。V在正常位置的磁矩对它们自身与缺陷原子之间的距离敏感。