Structures and magnetic moments of Fe-C clusters

The structures and magnetic moments of small FeC_N (N=1–8) and Fe₂C_N (N=1–6) clusters have been obtained by all-electron density functional theory. For the FeC_N (N=1–8) clusters, except for FeC₂, the ground states are predicted to be linear structures with the Fe atom bonded at one end. For the Fe₂C_N (N=1–6) clusters, the lowest-energy geometries show significant odd-even alternation. The Fe₂C_N clusters with even N, plus Fe₂C, have cyclic planar structures with transannular bonds. The Fe₂C_N clusters with odd N (N=3,5) prefer linear geometries with the two Fe atoms at the two ends. For all the clusters, analysis of the Mülliken population shows charge transfers from the Fe atom(s) to the C atoms with the magnetic moment lying primarily on the Fe atom(s).