Zhe Wang

Thank you for the comment, but that will ramp up the heating from 100K to 2000K. And it will not be a constant ramp up. Can it be increased constantly?

I think the command that Mr.zhe wang noted that is completely useful. I think it increases temperature constantly (at least near an constant rate) but if you can’t find a better solution you can do it in small smaller steps, for example:

timestep 1 # 1 fs

fix NVT1 all nvt temp 100 200 100

run 50000

fix NVT2 all nvt temp 200 300 100

run 50000

.

.

.

fix NVT19 all nvt temp 1900 2000 100

run 50000

You can also use loop command

You may know that it is not possible with lammps to set temperature exactly to the temperature you want. Even if you set both the start and stop temperatures to be equal, the system's temperature still fluctuates.

If you want to have more control on the rate, you can write a loop in your input file where you increase the temperature with small increments. You can find information on writing loops in lammps in the following link:

https://lammps.sandia.gov/doc/next.html

Dear Zhe Wang

How to calculate the heating rate if the timestep is different, for example, 0.25 fs?

Thanks!

Valentina Sierra

Respected fellow you can used this formula for any time steps

rate=temperature/(timestep*run)