(CoO)_n(n≤6)合金团簇的结构和磁性理论研究

Structural,electronic and magnetic properties of (CoO)_n( n ≤ 6) clusters

采用密度泛函理论中的广义梯度近似(DFT-GGA)对(CoO)_n(n≤6)合金团簇进行了系统的几何、电子结构和磁性质研究.研究结果表明(CoO)n(n≤6)团簇最稳定结构除(CoO)6团簇为三维立体结构外,其余团簇均呈二维平面结构,且(CoO)_n(n=1,2,3,4和6)结构均表现明显的钴氧分离特征,而(CoO)5团簇表现明显的Co—Co聚合和O—O分离特征.团簇的总磁矩在n=1,3,4时,以3μB为单元成倍增长,(CoO)5团簇显著降低,减小至1μB,(CoO)6团簇又有所增加,增大至6μB.(CoO)n(n≤6)团簇磁性变化的起因也从电荷转移、磁性耦合、电子差分密度和态密度进行了详细阐释.

The geometry structures,electronic properties,and magnetic properties of（CoO）n（ n ≤ 6） clusters are systematically investigated by using density functional theory with generalized gradient approximation.The results indicated that the（ CoO）n（ n ≤ 5） clusters are flat structures,except n =6,which is a three-dimensional structure.Additionally,the structures of（CoO）_n（ n = 1,2,3,4 and 6） present the apparent cobalt oxide separation characteristic,while the（CoO）5cluster shows the apparent Co—Co aggregation and O—O separation characteristic.The magnetic moments of the（ CoO）_n（ n = 1,3,4） are multiplied by 3 μB,and the magnetic moment of（CoO）5cluster is significantly reduced to 1 μB,whereas that of the（ CoO）6cluster increases again and gains 6 μBmagnetism.The origin of such a magnetic phenomenon is analyzed in detail by charge transfer,magnetic coupling,electron deformation density and partial density of states.