Impacts of Copper Position on the Electronic Structure of [Au25-xCux(SH)18]- Nanoclusters

Here, we use density functional theory to model the impact of heteroatom position on the optoelectronic properties of mixed metal nanoclusters. First, we consider the well-described [Au-25(SH)(18)](-) motif, and substitute Cu atoms at the three geometrically unique positions within the cluster. These clusters are atomically precise and show an electronic structure that is a function of both composition and heteroatom position. We then model clusters containing Cu substitutions at two positions, and demonstrate an additional and significant impact from heteroatom proximity with respect to one another. For each system, we report the formation energy, HOMO-LUMO gap, and energy level structure, and suggest how trends in these parameters may be explained using classic atomic descriptors such as electronegativity, analogous to design principles widely used in the field of organic electronics. Further, we use linear response time-dependent density functional theory to model the absorption behavior of each system in order to correlate these electronic properties with a convenient experimental readout.