Papers by Keyword: BPW91 Method

Abstract: Geometric structures of Fe_6-xSi_x(x=1-5) clusters have been systematically studied at the BPW91 level by density-functional theory (DFT). Calculated results show that the Fe atoms of the lowest-energy structures of Fe_6-xSi_x clusters tend to go together, and Si atoms tend to occupy surface site bonding with iron atoms as many as possible. Further, we analyze the stability of the lowest-energy structures of Fe_6-xSi_x clusters, and the corresponding results of the HOMO, LUMO as well as the HOMO-LUMO energy gap show that the Fe₅Si and Fe₄Si₂ clusters have special stability.

Abstract: The geometric structures and electronic properties of Si doped Fen (n=2-7) clusters have been systematically studied at the BPW91 level in density-functional theory (DFT). Calculated results show that an Si impurity does not change the ground-state structure of small iron clusters and prefers to occupy surface site bonding with iron atoms as many as possible. The second-order energy difference and the vertical ionization potential show that n=4 and 6 are magic numbers within the size range studied, but the maximum value occurs at n=4 for the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital(LUMO). It is found that the hybridization intensity between Si and Fe atoms is relevant to the stability of clusters.

Abstract: Theoretical study on the geometric structures and magnetic properties of small (FeAl)n (n=1-4) clusters has been carried out at the BPW91 level. In all the (FeAl)n clusters, the iron atoms are brought together, yielding a maximum of Fe-Fe bonds, and the aluminum atoms are located around a Fe core with a maximum of Fe-Al bonds which is different the bulk ordered FeAl alloy dominated by the Fe-Al bonds. As opposed to the bulk FeAl with non-magnetic, the small nano-clusters are highly magnetic moment dominated by Fe-Fe clustering.