71 lines
1.5 KiB
Plaintext
71 lines
1.5 KiB
Plaintext
# 2D overdamped active brownian particle dynamics (ABP)
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# with WCA potential
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variable gamma_t equal 1.0
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variable gamma_r equal 1.0
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variable D_t equal 1.0
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variable D_r equal 3.0
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variable seed equal 1974019
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variable fp equal 4.0
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variable params string ${gamma_t}_${gamma_r}_${D_t}_${D_r}_${fp}
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log log_WCA_${params}_2d.lammps.log
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units lj
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atom_style hybrid dipole sphere
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dimension 2
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newton off
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lattice sq 0.4
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region box block -16 16 -16 16 -0.2 0.2
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create_box 1 box
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create_atoms 1 box
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mass * 1.0
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set type * dipole/random ${seed} 1.0
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velocity all create 1.0 1 loop geom
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# more careful with neighbors since higher diffusion in abps
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neighbor 1.0 bin
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neigh_modify every 1 delay 1 check yes
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# WCA potential (purely repulsive)
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pair_style lj/cut 2.5
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pair_coeff * * 1.0 1.0 1.1224
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pair_modify shift yes
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# overdamped brownian dynamics time-step
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fix step all brownian/sphere ${gamma_t} ${gamma_r} ${D_t} ${D_r} ${seed} dipole
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# self-propulsion force along the dipole direction
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fix activity all propel/self dipole ${fp}
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fix 2 all enforce2d
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compute press all pressure NULL virial
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thermo_style custom step temp epair c_press
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#equilibration
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timestep 0.0000000001
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thermo 50001
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run 50000
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reset_timestep 0
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# MSD
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compute msd all msd
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thermo_style custom step temp epair c_msd[*] c_press
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timestep 0.00001
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thermo 10000
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# main run
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run 200000
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