how to build up crystalline molecular

Dear all,
Would you please tell me how to create crystalline molecular (crystalline chain) based on hex lattice for 2d problem or FCC (BCC) for 3d problem
when I build the crystalline molecular structure based on those lattice, atoms of chain will not be changed their position much after relaxation process, aren’t they?
Thanks for your help
Ha

Dear all,
Would you please tell me how to create crystalline molecular (crystalline
chain) based on hex lattice for 2d problem or FCC (BCC) for 3d problem
when I build the crystalline molecular structure based on those lattice,

there is too little information in your question.
do you know the space group? then it should
be straightforward to construct the positions
by writing a little program that applies the
various symmetry operations and eliminates
redundant coordinates.

atoms of chain will not be changed their position much after relaxation
process, aren't they?

depends. if somebody could tell (and in this generality) the result of
your simulations up front, why should there be a need to do them?

axel.

After trying running some lattice examples, I would like to do the problems a little more complicated than lattice
So, I would like to create a zigzag (or straight) chain (molecular) connecting atoms being on, e.g HEX lattice, such that when I equilibrate, the atoms on the chain aren’t moved. If so the system is not random
I don’t know what I’m thinking of is right or wrong?
Anw, Could you tell me a little detail about space group? I have never known it before
Thanks
Ha

After trying running some lattice examples, I would like to do the problems
a little more complicated than lattice
So, I would like to create a zigzag (or straight) chain (molecular)
connecting atoms being on, e.g HEX lattice, such that when I equilibrate,
the atoms on the chain aren't moved. If so the system is not random
I don't know what I'm thinking of is right or wrong?

what you are describing is effectively the difference between
a liquid and a crystal. now, whether you have one or the other
in your simulation depends on your choice of parameters.

Anw, Could you tell me a little detail about space group? I have never known
it before

why should i do this, if you can do this for yourself much better.
you can start here: http://lmgtfy.com/?q=space+group

axel.

Thanks!

LAMMPS has no internal commands to create bonds as you describe.
You will need to generate the molecular topology you want as
a pre-processing step and input a data file to LAMMPS.