# two type concentration gradient between fixed slabs. units lj atom_style atomic lattice fcc 0.8442 region box block 0 10 0 10 0 14 create_box 4 box create_atoms 1 box mass 1 1.0 mass 2 1.0 mass 3 2.0 mass 4 2.0 pair_style lj/cut 2.5 pair_coeff * * 1.0 1.0 2.5 # subdivide box. region lowfix block 0 10 0 10 0 1 region upfix block 0 10 0 10 13 14 region lowmov block 0 10 0 10 1 2 region upmov block 0 10 0 10 12 13 region wedge prism 0 10 0 10 2 12 0 10 0 # assign atom types set region upmov type 1 set region upfix type 2 set region wedge type 3 set region lowfix type 4 set region lowmov type 3 # group of moving atoms region move block 0 10 0 10 1 12.999 group move region move # set up MD. velocity move create 1.0 87287 rot yes mom yes neighbor 0.3 bin neigh_modify every 10 delay 0 check yes # temperature ramp for melting fix 1 move nvt temp 1.0 4.0 0.1 # allow diffusion only in x and y, restrain z fix 2 move spring/self 10.0 z dump id all atom 500 dump_gradient.lammpstrj thermo 1000 thermo_style custom step temp f_2 # ramp up the temperature run 50000 unfix 1 # done with ramping up T fix 1 move nvt temp 4.0 4.0 0.1 run 100000