中文摘要：

采用密度泛函理论方法，在BPW91/LANL2DZ水平下详细研究了PtnAl （n=1-8）团簇的几何结构、稳定性和电子性质。同时，分析了团簇的结构演化规律、平均结合能、二阶能量差分、能隙、磁性、Mulliken电荷和电极化率。结果表明：除Pt2Al外，所有PtnAl （n =1-8）团簇的基态几何结构都可以用Al原子替换Ptn＋1基态构型中的Pt原子得到，且Al原子位于较高的配位点上。二阶能量差分、能隙的分析结果表明， PtAl和Pt4 Al团簇相对其他团簇具有较高的稳定性。 Mulliken电荷分析表明， Al原子所带的电荷转移到Pt原子上， Al原子是电荷的捐赠者。磁性的分析说明，单个Al原子的加入对Ptn团簇的平均每原子磁矩随尺寸的变化趋势没有影响，但总体上降低了Ptn团簇的平均磁矩。极化率的研究表明，富Pt团簇的非线形光学效应强，容易被外场极化。

英文摘要：

The geometries, stabilities and electronic properties of PtnAl （n = 1-8） clusters are calculated using density functional theory at BPW91/LANL2DZ level. The stabilities of the ground states of PtnAl （n = 1-8） clusters are discussed by means of the binding energy, the second difference in energy and energy gaps, and the magnetic properties. Mulliken charges are studied. The growth patterns for different sized PtnAl （n = 1-8） clusters are of Al-substituted Ptn＋1 clusters and they keep a similar framework of the most stable Ptn＋1 clusters except Pt2Al. Al atoms in the ground state PtnAl isomer tend to occupy the most highly coordinated positions. The analyses of stabilities show that PtAl and Pt4Al are more stable than other clusters. Mulliken population analysis shows that charges are transferred from Al atoms to Pt atoms, which indicates that Al atom acts as electron donor in all PtnAl clusters. The analysis of magnetic property shows that doping an Al atom reduces the average atomic magnetic moment of the host Pd cluster. Pt-rich clusters which have a strong nonlinear optical effect and are easy to polarize by external electromagnetic field.