Structure and properties of cobalt clusters up to the tetramer: A density-functional study

All-electron calculations have been performed on cobalt clusters up to the tetramer using the local and generalized gradient correction spin density formalisms. These clusters present an abundance of low-lying states. In the case of Co-4, we have found that two and three-dimensional structures are energetically very close. Symmetric structures exhibit high degeneracy. Jahn-Teller deformations have hence been investigated and have been found to play an important role in such transition-metal clusters. General trends in the magnetic moment per atom and in the attachment energy have been elucidated.