[lammps-users] Thermal Conductivity

Hi,

I am trying to calculate thermal conductivity using Muller-Plathe method implemented in Lammps. My script is given below. Thermal conductivity can be calculated as

Thermal_conductivity(K)=-Heat_Flux/Temp_Gradient

With my script I can get the temperature gradient (delta_T/delta_Z). But how should I get Heat_Flux? Any help will be highly appreciated.

  #3-D Carbon Nanotubes
dimension 3
boundary p p p
units metal

atom_style atomic
newton on

read_data CNTCord.xyz

# Potential
pair_style airebo 3.0 1 0
pair_coeff * * CH.airebo C

kspace_style none

mass 1 12.0
neighbor 2.0 bin

velocity all create 300 6549325

# Equilibrate in NVT with Langevin thermostat
fix 1 all nvt 300 300 100
fix 2 all langevin 300 300 0.2 654678

thermo 10
run 2000
reset_timestep 0

# Computing thermal conductivity using Muller-Plathe alogorithm
unfix 1 # remove NVT
unfix 2 # remove Langevin

fix 3 all nve
thermo 10
run 1000
reset_timestep 0

fix 4 all thermal/conductivity 100 z 20 swap 100
compute ke all ke/atom
variable temp atom c_ke[]/(1.5*8.617e-5)
fix 5 all ave/spatial 10 100 1000 z lower 0.05 v_temp file tmp.profile units reduced

dump mydump all atom 100 dump.lammpstrj

run 100000