Versatile optimization of chemical ordering in bimetallic nanoparticles

Chemical ordering in bimetallic nanocrystallites can now be efficiently determined by density-functional calculations with the help of topological energy expressions. Herein, we deal with extending the usage of that computational scheme. We show that it enables one to structurally characterize bimetallic nanoparticles of less regular shapes than previously studied magic-type particles. In fcc Pd-Au particles of different shapes (cuboctahedral Pd58Au58, C3v Pd61Au61, cubic Pd68Au67, and truncated octahedral Pd70Au70), we identify the surface segregation of gold as the driving force to the lowest-energy chemical ordering. We applied the calculated descriptor values quantifying the segregation propensity of Au and energies of Pd-Au bonds in these ∼1.5 nm large particles to optimize and analyze the chemical ordering in 3.7-6 nm large Pd-Au particles. We also discuss how to predict the chemical ordering in nanoalloys at elevated temperatures. The present study paves the way to advanced structural investigations of nanoalloys to substantially accelerate their knowledge-driven engineering and manufacturing