Probing the electronic structures and properties of neutral and charged FeSi_n^(-1,0,+1) (n = 1-6) clusters using ccCA...

The equilibrium structures and electronic properties such as relative stabilities, electron affinities, and charge transfer of small neutral and charged FeSi_n^(-1,0,+1) (n = 1-6) clusters have been systematically studied using the high level of the correlation consistent Composite Approach (ccCA) method. The lowest-energy geometries of these clusters can be regarded as "substitutional structure." It is derived from Si_n + 1(and/or Si^-_n + 1) clusters by replacing a silicon atom with an iron atom. The adiabatic electron affinities (AEAs) and the adiabatic ionization potentials (AIPs) have also been predicted by ccCA schemes for FeSi_n(n = 1-6) and their ions. The dissociation energies of an iron or a silicon atom from the ground-state structure of FeSi_n clusters have been evaluated to check relative stabilities of FeSi_n^(-1,0,+1) (n = 1-6) clusters. Compared with other clusters, neutral and charged FeSi₂ possess higher stability. As for the neutral clusters and the negatively charged ions, the theoretical charges of the iron atom in FeSi_n (n = 1-6) species (except for FeSi and FeSi₂^-) show that silicon clusters act as an electron donor. For the cationic species, however, the charge transfers from iron atom to silicon clusters (except for FeSi₃⁺) show that the iron atom acts as electron donor.