Energetic and structural analysis of 102-atom Pd-Pt nanoparticles*

We present an extensive study of the structural and energetic changes of 102-atom \textit{Pd}$_{m}$\textit{Pt}$_{102-m}$ nanoparticles as a function of composition $m$, where the interatomic interactions are modeled with the many-body Gupta potential. The minimum energy structures are obtained through a genetic algorithm. The excess energy is calculated, as well as the pair distribution function $g(r)$. The radial distribution of the atoms is computed for each composition; the result indicates a multi-layer segregation for some compositions, with a shell growth sequence as follows: a core with a small number of Pd atoms is followed by an intermediate shell of Pt atoms and the external shell consists of Pd atoms. A region where Pd and Pt atoms are mixed is observed between the outermost and intermediate shells. Furthermore, the pure \textit{Pd}$_{102}$ and \textit{Pt}$_{102}$ nanoparticles have the same structure, while a variety of different structures are observed for the bimetallic clusters.