Core-shell and matryoshka structures in MgNi nanoalloys: a computational study

The structures of MgNi nanoparticles are searched for by a computational methodology combining atomistic modeling, global optimization searches and density-functional theory (DFT) calculations. Sizes of up to 45 atoms are considered for several different compositions. Core-shell structures are found in most cases. However, there are also exceptions, such as the three-shell high-symmetry matryoshka clusters Mg@Ni-12@Mg-32 (of anti-Mackay icosahedral geometry) and Mg@Ni-12@Mg-14 (of tetrahexahedral geometry). Other high-symmetry structures comprise the core-shell cubic Mg8Ni6, the tetrahexahedral cluster Mg14Ni13 and the pentadocahedral cluster Mg21Ni12. The results of the atomistic models are compared with DFT calculations, obtaining a good agreement.