Equilibrium structure and bonding of small iron-carbon clusters

The equilibrium geometries, binding energies, and electronic structure of neutral FeCn (n less than or equal to 3) clusters have been calculated self-consistently using ab initio molecular orbital theory. The exchange and correlation contributions to the total energy were computed using both the density functional method (with and without nonlocal correction) as well as the Hartree-Fock-Moller-Plesset theory. All levels of theory predict the equilibrium geometries to be cyclic. The binding energies, bond lengths, and the Mulliken charges obtained from both methods of calculations are also in agreement. The results are compared with recent mobility and photoelectron spectroscopy experiments. (C) 1996 American Institute of Physics.