units metal dimension 3 atom_style atomic boundary p p p region simbox block 0 25 0 25 0 35 units box create_box 2 simbox lattice fcc 5.0 region lower_layer block 0 15 0 15 0 20 units box create_atoms 1 region lower_layer mass 1 1.0 lattice bcc 3.0 region upper_layer block 0 15 0 15 20 35 units box create_atoms 2 region upper_layer mass 2 1.0 pair_style lj/cut 2.5 pair_coeff * * 1.0 1.0 velocity all create 300 25674 dist uniform fix 1 all nve dump 1 all atom 1 dump.atom run 1000