problem with non stable results in calculation of thermal conductivity using green-kubo method

Dear lammps users

I am working on the calculation of thermal conductivity using green-kubo method. At first steps the magnitude of thermal conductivity is approximately close to the experimental magnitude. But there is a problem. As I increase the simulation time, the final result decreases continuously. For example the exact result is 0.5 and the MD result is 0.4 at first iterates. But by increasing the time it changes to 0.39 0.38 0.36 0.35 and so on. I have attached the MD input code and the log file to this email. I don’t know why this happens. Any one can help me with this?

Thank you

in.input1 (1.99 KB)

log1.lammps (25.7 KB)

There is no guarantee that a simulation and its model for a materials will converge

to an expt value, even if you are doing the GK part perfectly correct.