Respected lammps users, During melting of iron when I use the temperature fixes are not controlling average and instantaneous temperatures; Applied values differs by a very huge differenced compared to applied in fix, nvt and velocity seed command.
velocity water create 3000 12345 mom yes rot yes
velocity water scale 3000
fix 7 water temp/rescale 100 1500 1500 0.02 0.7
fix 1 all nvt temp 3000 3000 1
what should be used to control average temperature properly near to the applied in commands?
Do not apply two thermostats with different target temperature to the same atoms. This makes no sense.
Also, please do not use fix temp/rescale for anything meaningful. It is a very bad thermostat algorithm for almost anything. The fact that is gives your system a regular “kick” and thus acts a bit like sticking a giant vibrator into your simulation can cause all kinds of problems.
Most MD software packages have it include merely because it is so easy to implement and thus they implement it first before implementing some more complex and proper thermalization algorithm.