[lammps-users] Separate temperature coupling


Is it possible to separately couple the temperature of different groups
using NPT dynamics? It seems like it should be possible since fix npt can
be applied to different groups; however when I try the system quickly


One problem is that the pressure is always a global computation on all atoms.
If you do fix 1 npt on one group of atoms and fix 2 npt on the remainder
the time integration (update of x,v) will only happen once for each atom,
but the pressure will get computed twice and the atoms will be dilated twice.

Seems kind of odd, but I don't know why it would blow up.

You might try the NPT fix on one group and a NVE fix on the other
group to begin and see what happens ...