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1

Hi all,

   I have a doubt about specifying the atom type to a group of atoms. So,
in a detail, I have 500 atoms of type 1 and 900 atoms of type 2 where
the atom style between type 1 and type 2 is 'angle'. Now I want to
include a third type in this section. where ,say, 300 atoms from type 1
and 500 atoms from type 2 ( who are basically part of a different atom
type) are part of a different type. I want to apply a fix command on
this 3rd type of atoms. But the previously mentioned type must not get
altered .So, the question is, can a single or a group of atom can
belong to two different atom types? Is there any preferred way of doing
this ?

thanks,

2

Dear Saikat:

An atom cannot be assigned to two types simultaneously, because this would mess up the calculations of forces and energies. However, it is always possible to assign atoms to multiple groups simultaneously using the “group” command. So if you can define the specific atoms to be assigned to the new group which will have the fix associated with it, then you can then use the group ID with the fix command to isolate the effect of the fix to the desired atoms.

—AEI