氧桥联稀土钆双核配合物磁学性质的密度泛函理论研究

Density functional theory study on the magnetic properties of rare earth gadolinium dinuclear complexes with oxygen bridges

采用密度泛函理论结合对称性破损态方法,选用氧桥联稀土钆双核配合物为研究对象,通过与实验值比较,探讨了不同泛函与基组对计算磁耦合常数的影响.结果表明,在B3LYP/TZV水平下(Gd为SARC-TZV),相对论效应采用DHK2方法,计算结果与实验测量值-0.022 5cm^(-1)最接近.不同体系测试结果显示,可在该水平下预测新合成稀土钆双核配合物的磁学性质.Mulliken自旋密度分析可知磁中心Gd以自旋极化为主.键级分析表明,2个磁中心之间的磁耦合作用通过桥联氧原子的超交换作用实现.分子磁轨道分析显示2个磁中心间存在较强的轨道相互作用,其磁轨道主要是由钆原子的4f_z^3,4f_z^2_x轨道和桥联氧原子的2pz轨道组成.

Rare earth gadolinium（Gd）dinuclear complexes with oxygen bridges（Gd—O—Gd）were selected as the research object on the baeis of the density functional theory combined with broken symmetry method.Based on the comparison between the computational and experimental values,the influence of functional and basis set on the calculation of magnetic coupling constant was comprehensively investigated.The results showed that the value of ferromagnetic Jwas in excellent agreement with the experimental value of-0.022 5cm-1 at the level of B3LYP/TZV（Gd as SARC-TZV）and relativistic effect using DHK2 method.Moreover,the test results of different systems indicated that at B3LYP/TZV level we could predict the magnetic properties of the newly synthesized rare earth Gd dinuclear complexes.The results of Mulliken spin density analysis indicated that magnetic center Gd was mainly dominated by spin polarization.The Mayer bond order analysis results showed that the magnetic coupling function between two magnetic centers was implemented by the superexchange function of bridged oxygen.Moreover,the analysis of molecular magnetic orbit demonstrated the existence of relative strong orbital interactions between the two magnetic centers.The magnetic orbit mainly consisted of the 4fz3 and 4fz2 orbits of Gd and the 2p_z orbit of bridged oxygen atom.