## Two pair potential vs many body potential Two body potential (like LJ) exhibit big failure when describing metals, like - mechanical properties different - vacancy formation energy in 2-body potential ~ cohesive energy, in metal very small - Melting temperature smaller for metal, estimated from $E_c / k_B$ - 2 body system gets higher evaporation rate at surface. Also, different packing leads to different properties, this cannot be shown in 2-body potential (i.e., 2b potential cannot differentiate FCC and HCP!) So a different potential would be necessary to describe metal. And that is EAM, [[Embedded atom method and the Glue potential|Embedded atom method]]