Optical Properties and Chemical Ordering of Ag–Pt Nanoalloys: A Computational Study

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.