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[lammps-users] Need help with understanding the run start/stop implement
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[lammps-users] Need help with understanding the run start/stop implement

From: "Chilakalapudi, Syamal Praneeth (INT)" <syamal.chilakalapudi@...1550...>
Date: Fri, 13 Apr 2018 18:15:43 +0200

Hi all,

I am trying to ramp temperature in multiple runs using the run start/stop command, like mentioned here and here.
I currently use the 5Feb18 version of LAMMPS. To give you a rough idea of what I am doing:

<initalisation, thermo, minimize>
reset_timestep 0

fix             f1 all nve
fix             f2 all temp/berendsen 3000 400 0.1

label l1
variable a loop 2
fix     deposit <some atoms at some rate>
run     20000 start $(step) stop 40000
#instead of run 20000
next    a
jump l1

There is definitely a difference between using two separate runs, and using the run start/stop command.
However, what I am unable to see is a uniform ramping over the entire 40000 time steps.

I have attached T vs time plots relevant to this discussion:

  1. Img1: Run 40000 steps with no break (and this is how I want the subsequent runs to resemble).
  2. Img2: Run 40000 steps. Using run start/stop, make 2 runs of 20000 steps each.
  3. Img3: Two separate runs of 20000 steps. Total steps still remains at 40000.

Is this the expected behavior? If yes, what must I do to make multiple runs which still resemble a single run?

Thanks a lot for your time.



Karlsruhe Institute of Technology (KIT),
Institute of Nanotechnology (INT)
M.Sc. Phys. Syamal Praneeth Chilakalapudi
Building 640, Campus North,
Hermann-von-Helmholtz-Platz 1,
76344 Eggenstein-Leopoldshafen, Germany

Phone: +49 721 608-28115

KIT---the research university in the Helmholtz Association

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