posted on 2015-04-16, 00:00authored byMichael
J. Hartmann, Hannu Häkkinen, Jill E. Millstone, Daniel S. Lambrecht
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 [Au25(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.