[lammps-users] heat transfer in silver

Dear All

In order to know the thermal conductivity for silver, I ran a chunk of silver. And using langevin thermostat on the left silver wall to maintain high temperature and same to right ends of the silver wall to maintain low temperature. Then I expect to see the temperature gradient in the silver. But mine results show that there is a temperature jump between the wall I thermostat and nearby wall layer. See the scripts and picture below. I don’t know why? It’s the same materials. Why there is a temperature jump? Is it numberical? Is it because of the thermostat?

units metal
boundary p p f
atom_style full
read_restart 300eq.restart.500000
pair_style eam
pair_coeff 1 1 Ag_u3.eam
region hol block INF INF INF INF -1 1 units box
region col block INF INF INF INF 22 23 units box
group ho-layer region hol
group co-layer region col
group hotwall id <= 324
group coldwall id >= 1621
group myall subtract all ho-layer co-layer
timestep 0.004
fix 3 hotwall langevin 310 310 0.01 8766790
fix 4 coldwall langevin 290 290 0.01 6757890
fix 5 myall nve
compute ke all ke/atom
variable temp atom c_ke[]/1.51.6/1.380650310000
fix 76 all ave/spatial 1 197000 200000 z lower 0.01 v_temp file tmp_heat units reduced
run 2000000

export.wmf

There is no plot attached. You have chosen
a big timestep for EAM. Also a small damping
constant (2.5 timesteps) for langevin.

Steve

export.wmf (9.07 KB)