forked from lijiext/lammps
66 lines
1.3 KiB
Plaintext
66 lines
1.3 KiB
Plaintext
# sample LAMMPS input script for viscosity of 2d LJ liquid
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# Green-Kubo method via fix ave/correlate
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# settings
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variable x equal 20
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variable y equal 20
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variable rho equal 0.6
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variable t equal 1.0
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variable rc equal 2.5
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variable p equal 400 # correlation length
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variable s equal 5 # sample interval
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variable d equal $p*$s # dump interval
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# problem setup
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units lj
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dimension 2
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atom_style atomic
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neigh_modify delay 0 every 1
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lattice sq2 ${rho}
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region simbox block 0 $x 0 $y -0.1 0.1
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create_box 1 simbox
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create_atoms 1 box
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pair_style lj/cut ${rc}
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pair_coeff * * 1 1
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mass * 1.0
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velocity all create $t 97287
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# equilibration run
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fix 1 all nve
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fix 2 all langevin $t $t 0.1 498094
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fix 3 all enforce2d
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thermo $d
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run 10000
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velocity all scale $t
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unfix 2
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# Green-Kubo viscosity calculation
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reset_timestep 0
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variable pxy equal pxy
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fix SS all ave/correlate $s $p $d &
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v_pxy type auto file profile.gk.2d ave running
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variable scale equal 1.0/$t*vol*$s*dt
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variable v11 equal trap(f_SS[3])*${scale}
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thermo_style custom step temp press pxy v_v11
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run 500000
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variable eta equal v_v11
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print "running average viscosity: ${eta}"
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