Structure and non-collinear magnetism of iron linear chains

Atomic structures and non-collinear magnetic moments are calculated by the first principle molecular dynamics for Fe5 and Fe6 linear chains with several fixed and free chain-lengths. The dimerization appears in the optimized atomic structures of all the chains. For the Fe5, the magnetic arrangement is parallel for a large chain-length and changes to non-collinear with decreasing the chain-length. For the Fe6, the magnetic arrangement is antiparallel in a unit of dimer for a small chain-length and changes to non-collinear with increasing the chain-length. These magnetic behaviors are simulated by a simple J1-J2 Heisenberg model