Au_nDy(n=6-15)团簇结构演化和理化性质的第一性原理研究

Structural evolution and physicochemical properties of Au_nDy(n=6-15)clusters:a first-principles study

为了研究Dy原子掺杂金基小团簇的理化性质的尺寸依赖效应,以期能将特异性质理解并推广至其他重镧系单原子掺杂的不同尺寸金基小团簇上。利用第一性原理自旋极化计算以及从头算进化模拟结构预测方法,研究了Au_nDy(n=6-15)团簇的结构、稳定性、磁性和化学活性。结合能计算结果表明掺杂Dy原子使Aun团簇更稳定。Au_nDy约5μB左右的高磁矩主要归结于高度局域的Dy-4f电子的贡献。Dy-4f电子的自旋-轨道劈裂以及晶体场作用使得Au6Dy不再是绝对平面结构。与纯Aun+1团簇相比,Au_nDy的HOMO-LUMO能隙比Aun+1有所减小,d带中心有所提升,这表明Au_nDy具有更好的化学活性和催化能力。

The size-dependence of physicochemical properties of AunDy（n=6-15）clusters have been explored to shed some light on other gold clusters doped by a single heavy lanthanon atom.The structure,stability,magnetism and chemical activity of AunDy（n=6-15）have been systematically studied by carrying out the first-principles spin polarization calculations and ab-initio evolutionary structure simulations.The binding energy results show that the dopant Dy atom makes Aunhosts more stable.The magnetic moment of about 5μB for AunDy clusters mainly origins from the highly localized Dy-4 felectrons.The spin-orbital interaction and spilt crystal field effect on Dy-4 felectrons cause Au6 Dy no longer an absolute planar structure.The HOMO-LUMO energy gaps of Au6 Dy are narrower than those of pure Aun＋1,while the d-band centers are normally increased,indicating that AunDy clusters have better chemical activity and catalytic ability.