Understanding the elusive magnetic behavior of manganese clusters

Manganese is a multifarious element and presents a large variety of behaviors. With the aim of understanding the complex behavior, we performed a systematic study of the magnetic solutions of the manganese dimer as a function of the interatomic distance. The calculation is performed within the framework of an ab initio calculation. We show that a remarkable interplay between different magnetic couplings leads to a transition between antiferromagnetic and ferromagnetic couplings as a function of interatomic distance. We present the electronic spectra for the two configurations for different interatomic distances and show clearly the role of the 4s to 3d electron transfer to stabilize the antiferromagnetic solution at short distances. Our results are in good agreement with experiment.