X掺杂团簇B_(n+1)(n=1〜11;X=Be,Mn)的密度泛函理论研究

Density functional theory study on X-doped B_(n+1)clusters(n=1〜11;X=Be,Mn)

本文利用密度泛函理论对B_(n)X(n=1~11;X=B, Be, Mn)基态结构、稳定性、电子构型与磁性开展了系统研究.结果表明:团簇B_(n)X(n=5~11;X=Be, Mn)中的X原子均位于高配位,B_(n)Be的基态构型为多重度为1或2的低重态;团簇B_(n)X的平均结合能均随尺寸的增大而逐渐增大,n取值相同时,B_(n+1)团簇的平均结合能最高.HOMO-LOMO能隙结果表明,掺杂铍原子、锰原子有利于提高纯硼团簇的化学活性;团簇BBe中的Be原子是电荷的受体,团簇BMn中Mn原子轨道电子表现出显著的spd杂化;团簇B_(n)X(X=B, Be)中的开壳层结构磁矩主要由2p轨道贡献.团簇BMn均为开壳层结构,总磁矩主要由Mn3d轨道贡献.随着团簇B-Mn尺寸的增大,Mn原子的配位数增大,B-Mn平均键长增大,Mn3d轨道磁矩减小而导致团簇的总磁矩减小.

The ground state structures,stabilities,electronic configurations and magnetic properties of B_(n)X clusters(n=1〜11;X=B,Be,Mn)have been systematically investigated by density functional theory.The results show that the X atoms are all located with high coordination number in B„X clusters(n=5〜11;X=Be,Mn).The lowest energy structures of B_(n)Be are low spin multiplicity states with multiplicities of 1 or 2.The average binding energies of B_(n)X clusters are increasing with increased size.When n is the same,the cluster B_(n+1)has the highest average binding energy.The energy gaps of B_(n)X clusters indicate that the stability of B_(n+1)is increased by X-doping(X=Be,Mn).The Be atom is the acceptor of charges in B_(n)Be clusters.The orbital electrons of Mn atoms in B_(n)Mn clusters exhibit significant spd hybridization.The magnetic moments of B_(n)X clusters(X=B,Be)with open-shell structures are mainly contributed by 2p orbitals.The electronic structures of B-Mn clusters are all Open shell,and the magnetic moment are mainly contributed by Mn3d orbitals.The coordination number of Mn atoms and the average bond lengths of B-Mn increased with size increasing.Accordingly the magnetic moment of B_(n)Mn clusters decreased by the reduction of Mn3d orbital magnetic moment.