Cr2Gen- (n=15-20) clusters with two Cr atoms exhibited antiferromagnetic coupling

In this work, we investigated the structural evolution, electronic and magnetic properties of Cr2Gen- clusters for n = 15-20 by using density functional theory (DFT) calculations. Low-energy structures for these clusters were fully searched through a self-developed genetic algorithm code combined with DFT calculations. The calculations show that all the two Cr atoms prefer to stay together to form a strong Cr-Cr bond, which-except for size 20-is shorter than the nearest neighbor distance in Cr bulk. Sizes 15 and 16 adopt a wheel-like structure as the structural motif with the extra Ge atoms capped on the top, while larger sizes (n = 17-20) prefer fullerene-like Cr-2@Ge-12 motifs. From the results of the average binding energies of Cr2Gen-, one can conclude that it is easier to form larger size clusters. In these lowest-lying isomers except for size 16, the two Cr atoms contribute opposite magnetic moments for the total magnetic moments of 1 mu(B), showing an antiferromagnetic state.

Automated summary

In this study, the structural evolution, electronic and magnetic properties of Cr2Gen- clusters (n = 15-20) were investigated using density functional theory (DFT) calculations. A self-developed genetic algorithm code combined with DFT calculations was used to fully search for the low-energy structures of these clusters. The calculations revealed that, except for size 20, the two Cr atoms prefer to form a strong Cr-Cr bond, which is shorter than the nearest neighbor distance in Cr bulk. Sizes 15 and 16 adopt a wheel-like structure with extra Ge atoms capped on the top, while larger clusters (n = 17-20) prefer fullerene-like Cr-2@Ge-12 motifs. The average binding energies of Cr2Gen- indicate that larger clusters are easier to form. In these lowest-lying isomers, except for size 16, the two Cr atoms contribute opposite magnetic moments, resulting in a total magnetic moment of 1 mu(B) and exhibiting an antiferromagnetic state.