Hi,dear friends

Can you help me to see whether this is good or enough to get the value of thermal conductivity of copper just for the phononic(vibrational) contribution, not consider the electrical part. Since I cannot find the value of the thermal conductivity of phononic part of copper, I just want to use lammps to get it. Thank you.

# setup the structure of sample

units metal

boundary p p p

atom_style atomic

lattice fcc 3.615 #specify lattice constant(800k)

region box block 0 5 0 5 0 5

create_box 1 box

create_atoms 1 box

pair_style eam/alloy

pair_coeff * * Cu_mishin1.eam.alloy Cu

neighbor 2.0 bin

neigh_modify delay 5

# setup variable

variable T equal 300

variable V equal vol

variable dt equal 0.004

variable p equal 200 # correlation length

variable s equal 10 # sample interval

variable d equal $p*$s # dump interval

# convert formula & units

variable kB equal 1.3806504e-23 # [J/K] Boltzmann

variable ev2J equal 96485.0/6.02214e23

variable A2m equal 1.0e-10

variable ps2s equal 1.0e-12

variable convert equal {ev2J}*{ev2J}/{ps2s}/{A2m}

# equilibration and thermalization

velocity all create 600 102486 mom yes rot yes dist gaussian

fix NPT all npt temp $T $T 10 aniso 0 0 1000 drag 0.2

thermo $d

run 100000

# 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 JJ all ave/correlate $s $p d &
c_flux[1] c_flux[2] c_flux[3] type auto file J0Jt.dat ave running
variable scale equal {convert}/${kB}/$T/$T/$V*s*{dt}

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_style custom step temp press v_Jx v_Jy v_Jz v_k11 v_k22 v_k33

run 100000

variable k equal (v_k11+v_k22+v_k33)/3.0

variable ndens equal count(all)/vol

print “average conductivity: $k[W/mK] @ T K, {ndens} /A^3”

Best wishes

Shengjie Tang

Department of Mechanical Engineering

University of Houston