[lammps-users] A problem about group number

Dear users:
When I am using Lammps,I find that the max number of groups LAMMPS assign is 32,Can I make this number larger?
Best regards
Yours CKG

Dear users:
     When I am using Lammps,I find that the max number of groups LAMMPS
assign is 32,Can I make this number larger?

you can answer this question yourself.

have a look at the file src/group.cpp

you'll find a line:

#define MAX_GROUP 32

you have three guesses what happens if you
change the 32 to something else and recompile...

cheers,
    axel.

No, groups are limited to 32. The masks for them are stored
in a 32-bit int. Changing that would be non-trivial.

Often, there are other ways to do the thing you want without groups, e.g.
by molecule ID, where there is no limitation.

Steve

Hi Steve,

I think it would be useful to add an “ungroup” command
to deregister an obsolete group. This may be helpfull in
certain circumstances.

L. Wan
2008/5/14

在08-5-9,Steve Plimpton <[email protected]…24…> 写道:

This would be possible, but non-trivial to implement.
Also, it might break some commands which check for
the group initially, but not later when it could have
disappeared.

Steve