Size and temperature effects on surface energy of Au and Fe nanoparticles from atomistic simulations

•Under the melting temperature, the fundamental sphere form of the Nanoparticle changed to other forms with low index facets.•Calculate the surface energy based on the model equation using the low facet-index that is defined by the coordination number.•The stability of the Nanoparticles was investigated with RDF and ADF calculations.•Comparison of the surface energy obtained for creating Nanoparticles from a fundamental sphere with the well-known morphologies constructed by ASE package.