A series of core−shell and layered ordered-phase AgPt
bimetallic clusters have been studied with Ag:Pt = 3:1 and 6:1 compositions
and sizes from 116 to 201 atoms. Chemical order has been established by
using a recent method (TOP) that assigns energy according to topological
degrees of freedom. Lowest energy structures determined by density
functional calculations are then studied by time-dependent density functional
theory to calculate optical properties. The present study shows that for AgPt
nanoparticles with core−shell structure the optical properties are sensitive to
both Pt concentration and cluster size. Spectral trends related to modifying
chemical order have also been identified.
