Inquiry about thermal conductivity calculation?

LAMMPS LAMMPS General Discussion
1

Hello everyone,

I have a question regarding thermal conductivity measurement with rNEMD method, given in this link. I can see that here, fix thermal/conductivity has been used twice with the same fix number. Apparently, the second time is to zero the energy accumulation. I am not sure why we have to use this command twice and with the same fix number. Basically, in my view is a waste of time. I have tried using this command only one time, but the thermal conductivity results seem to double in value, which is not correct. Also, I am not sure which result for these two runs is correct. I have to run this command for about 1000 ps to get the true values. So, basically, I am confused about which of these fix 3 commands should be run for this amount of time (1000 ps).

I will appreciate any help on this.

Thank you very much.

2

The command is not used twice, but the first fix instance is replaced/reset. What this does is documented in the manual. Check out the documentation for the fix command.

I have never before heard equilibration to be called a “waste of time”.

How can you talk about ps as a time unit when the input you are referring to is using reduced units?