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lammps/examples/KAPPA/in.heatflux
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in.heatflux
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# sample LAMMPS input script for thermal conductivity of liquid LJ
# Green-Kubo method via compute heat/flux and fix ave/correlate
# settings
variable x equal 10
variable y equal 10
variable z equal 10
variable rho equal 0.6
variable t equal 1.35
variable rc equal 2.5
#variable rho equal 0.85
#variable t equal 0.7
#variable rc equal 3.0
variable p equal 200 # correlation length
variable s equal 10 # sample interval
variable d equal $p*$s # dump interval
# setup problem
units lj
atom_style atomic
lattice fcc ${rho}
region box block 0 $x 0 $y 0 $z
create_box 1 box
create_atoms 1 box
mass 1 1.0
velocity all create $t 87287
pair_style lj/cut ${rc}
pair_coeff 1 1 1.0 1.0
neighbor 0.3 bin
neigh_modify delay 0 every 1
# 1st equilibration run
fix 1 all nvt temp $t $t 0.5
thermo 100
run 1000
velocity all scale $t
unfix 1
# thermal conductivity calculation
reset_timestep 0
compute myKE all ke/atom
compute myPE all pe/atom
compute myStress all stress/atom virial
compute flux all heat/flux myKE myPE myStress
variable Jx equal c_flux[1]/vol
variable Jy equal c_flux[2]/vol
variable Jz equal c_flux[3]/vol
fix 1 all nve
fix JJ all ave/correlate $s $p $d &
c_flux[1] c_flux[2] c_flux[3] type auto &
file heatflux.flux.profile ave running
variable scale equal $s*dt/$t/$t/vol
variable k11 equal trap(f_JJ[3])*${scale}
variable k22 equal trap(f_JJ[4])*${scale}
variable k33 equal trap(f_JJ[5])*${scale}
thermo $d
thermo_style custom step temp v_Jx v_Jy v_Jz v_k11 v_k22 v_k33
run 100000
variable kappa equal (v_k11+v_k22+v_k33)/3.0
print "running average conductivity: ${kappa}"
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