About in.langevin in KAPPA folder

Hi LAMMPS Users,

I hope you are okay with me asking another question, this one is much shorter, however, and more specific.

It’s regarding the in.langevin example input script in the KAPPA subdirectory of LAMMPS. I wanted to know why the two Langevin thermostats used to maintain a region at a high temperature (hot region) and another at a lower temperature (cold region) use the ‘all’ keyword for group ID. Shouldn’t the Langevin thermostats be configured only to work on a group of atoms (perhaps grouped by region) that are meant to be hot or cold?

I do not understand how the two regions are maintained at the desired temperatures. I’ve attached the input file for reference.

Many thanks and have a good day,

Tir

in.langevin (2.07 KB)

Hi LAMMPS Users,

I hope you are okay with me asking another question, this one is much
shorter, however, and more specific.

It's regarding the *in.langevin* example input script in the KAPPA
subdirectory of LAMMPS. I wanted to know why the two Langevin thermostats
used to maintain a region at a high temperature (hot region) and another at
a lower temperature (cold region) use the 'all' keyword for group ID.
Shouldn't the Langevin thermostats be configured only to work on a group of
atoms (perhaps grouped by region) that are meant to be hot or cold?

groups would not work for liquids where atoms move around​. the applying of
the themostat to a specific region is done with "biasing". please see the
temperature computes and the fix_modify commands and look up what that does
in the manual.

​axel.​