# simulation of LAMMPS logo units lj atom_style atomic dimension 2 # create 2d lattice, low density so diffuses lattice sq2 0.5 origin 0.25 0.25 0.0 region box block 0 31 0 7 -0.5 0.5 create_box 2 box create_atoms 1 box # LAMMPS letters via regions, convert to type 2 atoms region L1 block 2 3 1 6 -0.5 0.5 region L2 block 2 5 1 2 -0.5 0.5 region L union 2 L1 L2 region A1 block 6 7 1 6 -0.5 0.5 region A2 block 8 9 1 6 -0.5 0.5 region A3 block 6 9 3 4 -0.5 0.5 region A4 block 6 9 5 6 -0.5 0.5 region A union 4 A1 A2 A3 A4 region 1M1 block 10 11 1 6 -0.5 0.5 region 1M2 block 14 15 1 6 -0.5 0.5 region 1M3 block 10 15 5 6 -0.5 0.5 region 1M4 block 12 13 3 6 -0.5 0.5 region 1M union 4 1M1 1M2 1M3 1M4 region 2M1 block 16 17 1 6 -0.5 0.5 region 2M2 block 20 21 1 6 -0.5 0.5 region 2M3 block 16 21 5 6 -0.5 0.5 region 2M4 block 18 19 3 6 -0.5 0.5 region 2M union 4 2M1 2M2 2M3 2M4 region P1 block 22 23 1 6 -0.5 0.5 region P2 block 24 25 3 6 -0.5 0.5 region P3 block 22 25 3 4 -0.5 0.5 region P4 block 22 25 5 6 -0.5 0.5 region P union 4 P1 P2 P3 P4 region S1 block 26 29 5 6 -0.5 0.5 region S2 block 26 27 3 6 -0.5 0.5 region S3 block 26 29 3 4 -0.5 0.5 region S4 block 28 29 1 4 -0.5 0.5 region S5 block 26 29 1 2 -0.5 0.5 region S union 5 S1 S2 S3 S4 S5 region LAMMPS union 6 L A 1M 2M P S set region LAMMPS type 2 # LJ and other system parameters mass * 1.0 pair_style lj/cut 2.5 pair_coeff * * 1.0 1.0 2.5 timestep 0.005 neighbor 0.3 bin neigh_modify delay 0 every 1 check yes velocity all create 2.0 87287 loop geom thermo 100 dump 1 all atom 20 tmp.dump # run without integrator to "pause" the visualization run 100 # dissolve the lattice fix 1 all nve fix 2 all enforce2d run 1000 # run without integrator to "pause" the visualization unfix 1 unfix 2 run 200 # reverse the velocities and continue run # logo and lattice should reassemble within round-off errors variable vxflip atom -vx variable vyflip atom -vy velocity all set v_vxflip v_vyflip NULL fix 1 all nve fix 2 all enforce2d run 1000 # run without integrator to "pause" the visualization unfix 1 unfix 2 run 100