Mechanical and Electronic Properties of π-Conjugated Metal Bis(dithiolene) Complex Sheets

Using first-principles calculations, we have investigated the mechanical properties and electronic structures of π – conjugated metal bis(dithiolene) complex sheets (MC 4 S 4 ), where M = Ni and Pd. First, the sheets are much softer than graphene due to their large porosity. At zero strain, NiC 4 S 4 is a semiconductor with an indirect gap, while PdC 4 S 4 is a metal. Under either biaxial or uniaxial strain, our band structure analysis demonstrates that the band gap of the NiC 4 S 4 slowly decreases to zero with increased strain, which can be attributed to the gradual weakening of π-bonds of the sheet. However, the PdC 4 S 4 becomes a magnetic system beyond the deformation threshold that causes a plastic deformation along the X -axis. In addition, we also observe that both two-dimensional sheets undergo different types of nonreversible plastic changes under the uniaxial strains along the X - and Y -axes.