Dear LAMMPS-User,
I have some questions about the Example KAPPA.
https://github.com/lammps/lammps/tree/master/examples/KAPPA
In the example, the input file is
settings
variable x equal 10
variable y equal 10
variable z equal 20
variable rho equal 0.6
variable t equal 1.35
variable rc equal 2.5
variable tlo equal 1.0
variable thi equal 1.70
#variable rho equal 0.85
#variable t equal 0.7
#variable rc equal 3.0
#variable tlo equal 0.3
#variable thi equal 1.0
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
heat layers
region hot block INF INF INF INF 0 1
region cold block INF INF INF INF 10 11
compute Thot all temp/region hot
compute Tcold all temp/region cold
1st equilibration run
fix 1 all nvt temp $t $t 0.5
thermo 100
run 1000
velocity all scale $t
unfix 1
2nd equilibration run
fix 1 all nve
fix hot all langevin {thi} {thi} 1.0 59804 tally yes
fix cold all langevin {tlo} {tlo} 1.0 287859 tally yes
fix_modify hot temp Thot
fix_modify cold temp Tcold
variable tdiff equal c_Thot-c_Tcold
thermo_style custom step temp c_Thot c_Tcold f_hot f_cold v_tdiff
thermo 1000
run 10000
thermal conductivity calculation
reset langevin thermostats to zero energy accumulation
compute ke all ke/atom
variable temp atom c_ke/1.5
fix hot all langevin {thi} {thi} 1.0 59804 tally yes
fix cold all langevin {tlo} {tlo} 1.0 287859 tally yes
fix_modify hot temp Thot
fix_modify cold temp Tcold
fix ave all ave/time 10 100 1000 v_tdiff ave running
thermo_style custom step temp c_Thot c_Tcold f_hot f_cold v_tdiff f_ave
fix 2 all ave/spatial 10 100 1000 z lower 0.05 v_temp &
file profile.langevin units reduced
run 20000
and calculate the thermal conductivity by the following way.
(1) in.langevin
dQ = 8000 * 0.5*(0.905+0.947) / 100 / 18.82^2 / 2
8000 atoms
0.5*(0.905+0.947) = from log file =
ave of total in/out energy for 2 regions normalized by # of atoms
100 = 20,000 steps at 0.005 tau timestep = run time in tau
xy box area = 18.82^2
divide by 2 since energy flux goes in 2 directions due to periodic z
dTemp = 0.578 from log file for average Temp difference between 2 regions
dZ = 18.82
Kappa = 3.41
I have 2 questions.
The first question is that
ave of total in/out energy for 2 regions normalized by # of atoms = 0.5*(0.905+0.947)
How can I get 0.905 and 0.947 in the log file? I can’t find these two data in the log file
Are they from f_hot and f_cold command?
And the second question.
In this example.
fix hot all langevin {thi} {thi} 1.0 59804 tally yes
fix cold all langevin {tlo} {tlo} 1.0 287859 tally yes
fix_modify hot temp Thot
fix_modify cold temp Tcold
thermo_style custom step temp c_Thot c_Tcold f_hot f_cold v_tdiff f_ave
I want to know what kind of information that I get from f_hot and f_cold command in this example.
Temperature or energy?
Thanks a lot
Michael Hsieh