密度泛函理论在分子磁学中的应用--混合价三核锰配合物磁性的理论研究

Application of Density Functional Theory to Molecular Magnetism——Theoretical Study on Magnetic Properties of Mixed-valence Trinuclear Manganese Compounds

在对混合价化合物分类的基础上,将双核耦合模型推广到三核磁耦合体系,重点研究定域与离域两类混合价化合物的磁学性质.以混合价三核锰为例,应用密度泛函理论方法计算了定域与离域[Mn3O(O2CH)6L3]z+(L=pyridine;z=0)化合物的电子结构,得到与实验可比较的磁耦合常数J.结果表明,密度泛函理论(DFT)结合对称性破损(BS)方法可用于此三核混合价体系;对于完全离域的混合价MnⅡ3,Ⅲ,Ⅲ体系,必须考虑电子的离域作用对磁耦合的影响,其Hamiltonian量应该包含双交换参数B.为便于比较,同时计算了等价三核锰化合物[MnO(OCH)L]z+(L=pyridine;z=1)的磁学性质.

On the basis of classifying mixed-valence compounds,the dimer coupling model was extended to trinuclear magnetic coupling systems.Particular emphasis is placed on the well-localized and well-delocalized mixed-valence compounds.As a representative example,the electronic structure for well-localized and well-delocalized [Mn3O（O2CH）6L3]z＋（L=pyridine;z=0）model compounds were calculated via density functional theory,obtained the magnetic coupling constants J compared with experimental data.It is found that the density functional theory combined with broken symmetry approach can be applied to trinuclear mixed-valence systems considered.For well-delocalized mixed-valence MnⅡ,Ⅲ,Ⅲ3 system,the delocalization effect of the extra-electron on the magnetic coupling interaction must be considered,and thus the double exchange parameter B should be included in its Hamiltonian.For comparison the magnetic properties of the equivalence trinuclear [Mn3O（O2CH）6L3]z＋（L=pyridine;z=1）were also calculated.