Hi all,
in the examples/KAPPA/README file it is written that:
Here is how to extract Kappa from the log file output for each method.
The NEMD methods use the formula kappa = dQ * dZ/dTemp where dQ =
energy flux, and dTemp/dZ = temperature gradient.
(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 cannot understand why should we multiply by 8000 since f_hot and f_cold provide us with the cumulative energy added/subtracted to the atoms as they are thermostatted. Moreover, I cannot see a line in the input script (or in the log file) where averaging of the total in/out energy for 2 regions normalized by # of atoms is performed.
Many thanks for your help in advance.
Kind regards,
Michael