Hello,

I am following the langevin example to calculate the thermal conductivity of a material.

https://github.com/lammps/lammps/tree/master/examples/KAPPA

In the method you thermostat a hot and cold region:

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

And then following this part in the README:

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

Here’s my question: If you change the region sizes, the cumulative in/out energy will change…bigger regions will have more energy, smaller regions have smaller energies…so what number of atoms do you normalize by?

Thanks,

Stacey