Molecular dynamics and thermodynamic simulations of segregation phenomena in binary metal nanoparticles

An approach combining atomistic molecular dynamics (MD) and thermodynamic simulations has been applied to predict the distribution of components in binary Ni-Cu and Au-Ag nanoparticles consisting of 2000 atoms (of about 4 nm in size). The term 'thermodynamic simulation' has referred to solving, in some approximations, the Butler equation for a core-shell particle model. Both atomistic and thermodynamic approaches predict the surface segregation of Cu atoms in Ni-Cu nanoparticles and segregation of Ag to the surface of Au-Ag nanoalloys. Then, contrary to the Ni-Cu systems, some Au-Ag nanoparticles demonstrated an onion-like structure with the outer Ag monolayer. The results of MD and thermodynamic simulations agree with each other and with some available direct and indirect experimental data.