A first-principles calculation based on density functional theory is carried out to reveal the geometry, electronic structure and magnetic properties of aluminium nitride nanotubes ( AlNNTs) , whose Al/N atoms are substituted by 5d atoms (Al5d or N5d). The pure-AlNNTs and AlNNTs with Al vacancy (VAl) and N vacancy (VN) are also investigated for comparison. Results show that the local symmetry of Al5d system is similar to C3v, while the N5d system exhibits a large geometric deviation from C3v. When AlNNTs are doped by the same 5d at-om, the bonding energy of Al5d is higher than that of N5d;when 5d atoms substitute for Al/N atoms, the bonding energy of system decreases along with the atomic number growth. There exist obvious impurity energy levels in the band gap, and the densities of states ( DOSs) are presented. The total magnetic moment differs from each other when doped by different atoms, and the total magnetic moments of doped systems present a strong regulari-ty. The impurity energy levels and total magnetic moments are explained by the molecular orbital theory under C3v local symmetry.%采用基于密度泛函理论(DFT)的第一性原理计算方法,研究了5d过渡金属原子(Lu、Hf、Ta、W、Re、Os、Ir、Pt、Au、Hg)取代AlN纳米管( AlNNTs)中的铝原子或氮原子时体系的几何结构、电子结构和磁性性质；并且以理想AlN纳米管( AlNNTs)、Al缺陷体系( VAl )和N缺陷体系( VN )的结果作为对比。研究发现：5d 原子取代Al(Al5d)时体系的局域对称性接近于C3v,但是取代N(N5d)时体系的局域对称性偏离C3v对称性较大；当掺杂的5d元素相同时, Al5d的成键能比N5d的成键能大；当掺杂体系相同时(Al5d或N5d),其成键能基本上随着5d原子的原子序数的增大而降低；掺杂体系中出现了明显的杂质能级,给出了态密度等结果；不同掺杂情况的磁矩不同,总磁矩呈现出较强的规律性。利用C3v对称性和分子轨道理论解释了过渡金属原子取代Al时杂质能级的产生和体系磁性的变化规律。
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