Rigorous Extraction of the Anisotropic Multispin Hamiltonian in Bimetallic Complexes from the Exact Electronic
Rémi Maurice1, Nathalie Guihéry1, Roland Bastardis1
1Laboratoire de Chimie et Physique Quantiques, IRSAMC/UMR5626, Université de Toulouse III, 118 route de Narbonne, F-31062 Toulouse Cédex 4, France, Departament de Química Física i Inorganica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain, Laboratoire de Mathématiques, Physiques et Systemes, Université de Perpignan Via Domitia, 52 avenue Paul Alduy, 66860 Perpignan, France, and Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluis Companys 23, 08010 Barcelona, Spain.
Abstract:
The magnetic anisotropy of the [Ni2(en)4Cl2](2+) (en = ethylenediamine) complex has been studied using wave function based computational schemes. The spin-orbit state interaction methodology provides accurate ab initio energies and wave functions that are used to interpret the anisotropy in bimetallic complexes. The extraction of the anisotropic spin Hamiltonian is performed using the effective Hamiltonian theory. This procedure which has successfully been applied to mononuclear complexes enables one to solve the weak exchange limit. It is shown that the standard coupled spin Hamiltonian only describes a part of the anisotropy of the molecule. Important higher order terms such as the biquadratic anisotropic exchange should be included in the model for an appropriate description of the anisotropy.
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