[lammps-users] group command

Dear LAMMPS users,

I have 810 atoms in my simulation box, I need to create a group of atoms whose id’s are for example lower than 100 or higher than 700. The simulation run terminates with this error message “0 atoms in group id1”. My command is “group id1 >=700”. Does any body know about this problem?
Any help would be appreciated.

Best.
S.Yousefi.

Dear LAMMPS users,

I have 810 atoms in my simulation box, I need to create a group of atoms
whose id's are for example lower than 100 or higher than 700. The simulation
run terminates with this error message "0 atoms in group id1". My command is
"group id1 >=700". Does any body know about this problem?

yes. this is clearly a case of PEBCAC.

please read the group command documentation and use the group command correctly.

axel.

ps.: in case you have trouble with the acronym, check out:
http://www.urbandictionary.com/define.php?term=PEBCAC

Dear Somaiieh,

You should add name of your group atoms, e.g.

group upper id >= 700

do not use “id1” because id is keyword from Lammps, just use id.

best,
rizal

2010/12/26 Somaiieh Yousefi <[email protected]…24…>

I need to create a group of atoms whose id's are for example lower than 100 or higher than >700.

The <> option in the group command will give you atoms between
100 and 700. If you then subtract that group from "all" you will
get what you want.

Steve