Electronic and geometrical structure and magnetic ordering in passivated Mn12O12-acetate nanomagnets

We performed electronic structure calculations on several Mn12O12 and Mn12O12(COOH)(16)(H2O)(4) clusters to investigate the magnetic ordering and the role of the ligands in stabilizing the D-2 structure of the MnO core. Without passivation, an antiferromagnetic tower is more stable than the free D-2 Mn12O12 core, but the ligands stabilize the D-2 symmetry which leads to ferrimagnetic ordering and a net moment of 20 mu(B). Local Mn moments are presented and the electronic states most responsible for formation of the spin tunneling barrier are identified. (C) 1999 Elsevier Science B.V. All rights reserved.