The Simplified Calculation For The Molecular Magnetic Anisotropy Based On Spin Hamiltonian Theory

As a new soft magnetic material,molecule-based magnetic materials become a new branch of science,which has been studied by many physicist,chemist and biologist. Molecule-based magnets is a molecular compounds which can spontaneous magnetization under certain critical temperature Magnetic properties of molecule-based magnets not only has macroscopic Ferromagnet and Ferrimagnet,but also take an important role in microscopic magnetic exchange interaction,with the characteristics of small density, light weight, structural diversity, easy to process as well as light, electrical, heat, magnetic physical properties.so molecule-based magnets is likely to be used in microwave absorbing stealth, making the spacecraft, shielding materials electromagnetic and information storage materials, which has a great prospect in applied field. In this paper,mainly based on the spin Hamiltonian theory of the molecular magnetic Heisenberg model (namely isotropic exchange model),several aspects are carried out as follows:Based on the spin Hamiltonian theory,We take the magnetic ions in the molecular crystals,molecular structure,ligand field other factors which influence the molecular magnetism as the research object,we also take to the isotropic exchange term, Zeeman effect terms, into consideration establish two Magnetic exchange model, anisotropy of the single-ion spin Magnetic exchange model (modelⅠ) and molecular magnetic anisotropy the total spin exchange model (modelⅡ). respectively,The Hamiltonian can be expressed as: Where N is the number of magnetic ions of molecular crystals(This study focuses on the molecular clusters of N=2); Si,Sj is Magnetic ions spin angular momentum operator i,j, respectively; where is S=(?)Si the operator for angular momentum of molecular total spin,while the subscript x,y,z and single-ion spin or total spin component to corresponding, respectively;Di, Ei and gi are anisotropy of the single-ion in the axial and rhombic zero-field splitting parameters(namely commonly referred to D values and E values) and Lande factor g;Dt,Et and giso are molecular clusters the total spin anisotropy D values. E values and Lande factor giso.The article focuses on the research of molecular spin is 1 and moleculars cluster with N=2 the number of magnetic ions.Try to these two exchang models of analytical solution in uncoupled spin wave functions and in coupled spin wave functions representation method, repectively. To obtained analytically considering single ion spin anisotropic or total spin anisotropic.The susceptibilities and the magnetizations.including their reasonable magnetic parameters.Solving process in specific, the use of Mathematica and other mathematical programming tools to achieve the theoretical derivation of the two models, such as considering only isotropic items a simplified way (in this case consistent with the corresponding Heisenberg model) obtained with Van Vleck formula for the same results to test the correctness of our solution. Then analyzed the structures of several kinds of different ligands coordination complexes,such as Tris (2-methyl pyridyl)amine,Azide,(SCN-),dpmap-,oxamido.To the analytical solution fitting different ligands coordination complexes results of the magnetic parameters.Finally, We compare and discuss the results.