how to get full FCC single crystal after npt fix

Dear Lammps users,

I am new to lammps. I want to create a Cu single crystal that is FCC and relax it to 0k temperature and 0 bar pressure. But after the simulation, only half of the atoms are FCC and rest are disturbed. I also get lost atoms error many times by changing different parameters.

I will copy my input script, please see it and suggest some edits.

Thanks
Saurabh

Input file for uniaxial tensile loading of single crystal aluminum

Mark Tschopp, November 2010

------------------------ INITIALIZATION ----------------------------

units metal
dimension 3
boundary p p p
atom_style atomic
variable latparam equal 3.61

----------------------- ATOM DEFINITION ----------------------------

lattice fcc {latparam} region whole block 0 15 0 15 0 15 create_box 1 whole lattice fcc {latparam} orient x 1 1 2 orient y 1 -1 0 orient z 1 1 -1
create_atoms 1 region whole

------------------------ FORCE FIELDS ------------------------------

pair_style meam/c
pair_coeff * * library.meam Cu Cu.meam Cu

------------------------- SETTINGS ---------------------------------

compute peratom all pe/atom

Dear Lammps users,

I am new to lammps. I want to create a Cu single crystal that is FCC and relax it to 0k temperature and 0 bar pressure. But after the simulation, only half of the atoms are FCC and rest are disturbed. I also get lost atoms error many times by changing different parameters.

I will copy my input script, please see it and suggest some edits.

​your system does not proper continue through periodic boundaries​
​ and you have problems due to numerical instablities originating from placing the box boundaries on the lattice points. this leads to ambiguities and thus you have an imperfectly built crystal and lost atoms and related are the consequence. i’ve already pointed these issues out to you. gave you suggestions how to address this. the rest is your job, not ours.

axel.​