Interplay between structural and electronic properties of bundled Mo ₆S_9-xI_x nanowires

Using first principles density functional theory, we investigate the structural, electronic and magnetic properties of isolated and bundled Mo ₆S_9-x I_x nanowires with x = 3, 4.5, and 6. The unit cell of each system contains two Mo6 octahedra decorated with S and I atoms and two S₃ linkages. Due to the bistability of each sulfur linkage, finite-length nanowires or nanowire bundles exhibit many stable structural minima. We explore the structural stability, elastic behavior and electronic structure at all these minima for each composition x. We find that the axial strain and inter-wire interaction in bundles significantly modify the electronic structure. The most intriguing changes occur in nanowires with x = 4.5 and 6, which change from metal to semiconductor or undergo a magnetic transition upon axially stretching or compressing the nanowires or upon changing the inter-wire separation.