[lammps-users] fix langevin

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1

Hi,

I am running a heating simulation from 10 to 300 K with fix nve + fix langevin, After the heating process (100 nsec), I would like to run more at 300 K, however when I modify the fix langevin my system blows up (missing atoms). I am assuming that the velocities from the last step of the heating run, is not used at the beginning of the 300 K run.

Note: I don't have the same problem when I used fix nvt. It runs very smoothly.

Here is the fix nvt run:

fix 1 all nvt temp 10.0 300.0 100.0
dump 1 all dcd 1000 dump.dcd
restart 500000 tmp.restart.
min_style cg
minimize 1.0e-8 0.001 10000 1000000
run 2000000 post no
fix 1 all nvt temp 300.0 300.0 100.0
run 4000000 pre no upto

Here is the fix langevin that blows up:

fix 1 all nve
fix 2 all langevin 10.0 300.0 100.0 48279
dump 1 all dcd 1000 dump.dcd
restart 500000 tmp.restart.
min_style cg
minimize 1.0e-8 0.001 10000 1000000
run 2000000 post no
fix 2 all langevin 300.0 300.0 100.0 48279
run 4000000 pre no upto

Any ideas how to fix this?

Thanks in advance,
-burak

2

I don't see any problem with what you're using.
I would not use "post and pre no" on the run
commands.

I am assuming that the velocities from the last step of the heating run, is not used at the beginning of >the 300 K run.

This is not the case. Everything carries over to the next run.

Steve