Magnetic Anisotropy in a Cubane-like Ni₄ Complex: An Ab Initio Perspective

Magnetic anisotropy, in the absence of an external magnetic field, relates to degeneracy lift energy levels. In standard case transition metal complexes, this property is usually modeled by anisotropic spin Hamiltonian and one speaks “zero-field splitting” (ZFS) states. While mononuclear complexes has been extensively described means ab initio quantum mechanical calculations, literature on polynuclear studied with these methodologies rather scarce. work, advanced multiconfigurational wave function theory methods are applied compute ZFS ground S = 4 state actual tetranickel(II) complex, displaying a magnet behavior below 0.5 K. First, isotropic couplings computed spin–orbit coupling operator, full complex also clusters only two active nickel(II) centers, confirming occurrence weak ferromagnetic system. Second, single-site anisotropies cluster bearing site, showing that anisotropy axes not oriented optimal fashion for generating large uniaxial molecular anisotropy. Furthermore, possibility involving few local orbital excited states calculation assessed, actually opening way consistent manageable treatment state. Third, calculations performed occurring also, interestingly, revealing significant contribution lowest-lying orbitally 3 Overall, comparison experiment, reported results question common habit using structure, particular derived from crystallography parameters.