Structural Patterns in Carbon Chemisorption on an Icosahedral 2 Iron Cluster

Abstract

Carbon chemisorption on iron nanoparticles at small carbon coverage has been studied by using a Fe13 particle as a model because it possesses a nearly icosahedral geometry, and complications with additional effects associated with the surface inhomogeneity do not arise. The electronic and geometrical structures of Fe13Cn are computed for n = 0–20 using an all-electron density functional theory with generalized gradient approximation and a rather large basis set. It is found that the energetically preferred structures correspond to the formation of carbon dimers up to Fe13C12 and trimers up to Fe13C18 in octahedral configurations of the dimers and trimers with the Fe13 cluster being endohedral. The trend for the formation of carbon tetramers breaks at Fe13C20. We found that the dependence of the total energy on the total spin is nearly the same for Fe13 and Fe13C8. When the number of chemisorbed carbon atoms exceeds 6, chemisorption quenches the total magnetic moment to 36 μB from the value of 44 μB in the...