Hi, guys,
I found the Argon thermal conductivity values are accumulative and linear instead of constant value. The results are bothering me a few days. I could not figure out what is wrong place.
The conclutions i got are: I am sure my simulation reach equilibrium; And the temp profile are linear based on bins; the heat flux profile is linear; The temp gradient is constant.
I post my input file here:(temp profile,heat flux file and temp gradient are in the attchment)
NEMD simulation of Ar thermal conductivity
Initialization
units lj
dimension 3
newton on
boundary p p p
atom_style atomic
neighbor 0.3 bin
neigh_modify check yes
lattice fcc 0.844
region box block -4 4 -4 4 -4 4 units lattice
create_box 1 box
create_atoms 1 box
region hot block INF INF INF INF -0.5 0 units lattice
region cold block INF INF INF INF 3.5 4 units lattice
mass 1 1.0
velocity all create 0.71 458127641 mom yes rot yes dist gaussian units box
pair_style lj/cut 2.8
pair_coeff 1 1 1.0 1.0 # LJ parameters for Ar-Ar
fix temp all temp/berendsen 0.71 0.71 0.05
fix nve all nve
compute ke all ke/atom
variable temp atom c_ke/(1.5*1.0)
fix temp_profile all ave/spatial 1 100000 100000 z lower 0.5 v_temp file temp.profile units lattice
compute hot_temp all temp/region hot
compute cold_temp all temp/region cold
variable delta_temp equal c_hot_temp-c_cold_temp
fix delta_out all ave/time 1 100000 100000 v_delta_temp file delta_temp.dat -------------# temperature gradient
thermo_style custom step temp etotal vol
thermo_modify lost warn
thermo 100
Run
timestep 0.005
run 100001
unfix temp
fix heat_swap all thermal/conductivity 10 z 16
fix e_exchange all ave/time 10 10000 100000 f_heat_swap file e_exchange.dat -----------#Energy exchanged
variable thermal_conductivity equal f_e_exchange/(0.00510.02.0*f_delta_out)1.3806504e-23/(3.405e-103.405e-10)*sqrt(1.67e-21/6.633e-26) ---------# lj units to real units
fix thermal_conductivity_out all ave/time 100000 1 100000 v_thermal_conductivity file thermal_conductivity.dat
Run
run 10000000
Hopefully, somebody can give me some help. Thanks in advance!
Bests,
Eric
Thermocond_Ar.docx (20.5 KB)