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I am trying to heat up my system from 10K to 300K using the NPT ensemble. But the temperature doesn't reach 300K. What do you think is the problem?

This is my code for the heating part. However, the problem is the temperature is only reaching about 150K after the entire 30000 runs.

velocity        all create 10 416629

thermo          100
thermo_style    custom step temp press

fix             1 all npt temp 10.0 10.0 1.0 iso 0.0 0.0 10.0
run             10000
unfix           1

fix             2 all nve
run             5000
unfix           2

fix             1 all npt temp 10.00 300.00 1.0 iso 0.0 0.0 10.0
run             30000
unfix           1

fix             2 all nve
run             5000
unfix           2

fix             1 all npt temp 300 300.00 10.00 iso 0.0 0.0 100.0
run             10000
```
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    $\begingroup$ Run more time step with npt probably around 50000 or 100000 $\endgroup$ Apr 26, 2023 at 10:56
  • $\begingroup$ Ah I found the solution. I changed the Tdamp to $(100*dt) and it worked. Although, I don’t understand exactly what is happening. $\endgroup$ Apr 27, 2023 at 9:07
  • $\begingroup$ @anumoyganguly please write a self-answer. $\endgroup$ Apr 27, 2023 at 11:41
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    $\begingroup$ @anumoyganguly, tdamp represents the time damping factor for thermostats in LAMMPS MD simulations. The choice of tdamp influences how quickly it drives the system towards the desired temperature. As you didn't mention your timestep size, it is likely that your initial tdamp choice of 1.0 was too large, resulting in slower convergence and longer simulation times. By using $(100*dt) [As suggested by LAMMPS Manual, this should be good for most cases.], you adjusted tdamp to be 100 times the timestep size, which improved convergence and temperature control in your simulation. $\endgroup$ May 5, 2023 at 16:40

1 Answer 1

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The OP found an answer:

"Ah I found the solution. I changed the Tdamp to $(100*dt) and it worked. Although, I don’t understand exactly what is happening."

If someone would like to write an answer, I can delete this Community Wiki answer (you can just ask me in a comment on this answer, or click "flag" and "In need of moderator intervention" and explain yourself).

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