Structure of aluminum atomic chains - art. no. 195420

First-principles density-functional calculations reveal that aluminum can f orm planar chains in zigzag and ladder structures. The most stable one has equilateral triangular geometry with four nearest neighbors; the other stab le zigzag structure has wide bond angle and allows for two nearest neighbor s. An intermediary structure has the ladder geometry and is formed by two s trands. While all these planar geometries are more favored energetically th an the linear chain, the binding becomes even stronger in nonplanar geometr ies. We found that by going from bulk to a chain the character of bonding c hanges and acquires directionality. The conductance of zigzag and linear ch ains is 4e(2)/h under ideal ballistic conditions.