Tight-binding Ising modeling of the interplay between bulk ordering and surface segregation in Pt-Ag nanoalloys

•Fitting a Tight-Binding Ising Model with effective pair interactions depending on concentration able to reproduce the bulk phase diagram of Pt-Ag system: in particular its strong asymmetry as a function of composition and the peculiar L11 ordered phase.•Prediction of the silver surface segregation on (111) and (100) surfaces on top of the Pt-rich solid solution, the L11 ordered phase or the Ag-rich solid solution as a function of the concentration.•Prediction of the core-shell nanoalloys with silver shell and a core made of Pt- rich solid solution, ordered L11 phase or Ag-rich solid solution with increasing Silver concentration. A surprising pseudo-L11 phase has been obtained in a narrow composition range slightly lower than the one for the perfect L11 core where the L11 phase develops beneath each (111) cluster facets leading to an alternate staking of Ag-pure/Pt-pure concentric layers.