【摘要】 使用密度泛函理论(BP86)结合非平衡态格林函数(NEGF)方法研究金属串配合物[Cu2Pt(npa)4X2](X=Cl-(1),NCS-(2);npa=2-naphthyridylphenylamine)的电子结构和电子传输性质,研究发现:(1)由于轴向配体NCS-与Cu的结合比Cl-的强,使配合物1的Cu—Cu键比2的强而Cu—Pt键比2的弱,故1的π*Pt dxz/yz轨道与π*Cu-Cu能级差ΔE比2小.(2)1和2的传输通道均是β自旋的π*轨道,主要由π*Cu-Cu和π*Pt dxz/yz轨道组合而成.ΔE越小π*越离域,传输能力越强.在负偏压下和正偏压小于0.15 V时,1的电流大于2;但正偏压大于0.15 V后2的β电流显著高于1.(3)2具有较好的整流效应.ΔE越大,Pt→Cu方向的传输越容易,整流效应越强.正偏压下2的电流显著大于负偏压下的电流,0.15 V后2的整流比比1高10~40倍.(4)因ΔEβ<ΔEα,α自旋通道传输能力小于β自旋的,1和2具有良好的自旋过滤效应(高达80%~99%).更多还原

【Abstract】 The asymmetric heterometal string complexes [Cu2Pt(npa)4X2](X=Cl-(1), NCS-(2), npa=2-naphthyridylphenylamine) are suitable candidates for promising inorganic molecule rectifiers. The electronic structures and transmission properties of them were investigated by theoretical calculation using Density Function Theory BP86 and Non Equilibrium Green’s Functions method. The results revealed that:(1) Since the interaction between axial ligand NCS- and Cu atom is stronger than that of Cl—Cu, the Cu—Cu bond of complex 1 is stronger than that in 2, while its Cu—Pt bond is weaker than that in 2. Therefore, complex 1 has smaller energy gap ΔE between π*Pt dxz/yz and π*Cu-Cu orbital compared with that of 2.(2) The transmission channels of 1 and 2 both are β spin π* orbitals, which are mainly combination of π*Cu-Cu and π*Pt dxz/yz orbital. The smaller ΔE, the larger delocalization of π* channel, and hence the stronger transmission capacity. When the positive bias is less than 0.15 V and under negative bias, current of 1 is greater than that of 2 for the smaller ΔE of 1. However when the positive bias is larger than 0.15 V, current of 2 is significantly higher than that of 1 for the stronger delocalization of π* channel in 2.(3) The complex 2 has better rectifying effect. With a larger ΔE, the transmission of Pt → Cu direction is easier and the rectifying effect is stronger. Current of 2 under the positive bias is significantly greater than that in negative bias. When the bias is larger than 0.15 V, the rectified ratio of 2 is 10~40 times larger than 1.(4) With the ΔEβ smaller than ΔEα, the transmission capacity of α spin channel is less than β, and the effect of the spin filter will be stronger for the larger difference between ΔEβ and ΔEα. Both 1 and 2 have significant spin filter effect(up to 80%~99%).更多还原