Structure and energetics of small iron clusters

Electronic properties of Fe_2-10 clusters and their ions are described by an all-electron ab initio density functional theory computational analysis using the Handy's OPTX exchange and the gradient-corrected correlation functional of Perdew, Burke and Ernzerhof with a triple-zeta valence basis set plus polarization functions. Ground state structures, magnetic moments, dissociation energies, binding energies, IR vibrational spectra, vertical and adiabatic ionization energies, and electron affinities are reported. Two possible states for Fe₂ which are separated by 81.54 meV are described as possible Fe₂, while the septet (ground state) yields an accurate bond distance (error of 0.02 Å); the nonet yields a precise vibrational frequency (error of 10.1 cm^-1). Fe₂ binding energy (0.05 eV/atom error) more closely resembles experimental data than any other previously reported computational methods. In addition, the Fe₆ is found to be the most stable cluster within our set being analyzed.