question about lammps

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

2011/4/2 tangshengjie <[email protected]>:

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

no. you have to verify your procedure for yourself.
the best way to do this is to first try reproducing
some published (simulation) values, before doing
a simulation of a system that you don't know.

what would you respond to somebody asking you
about the validity of your results otherwise?
would you want to say "some random person
on the internet that i don't know, told me so"?

cheers,
    axel.