Atoms distortion at periodic boundary for some orientation

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1

Hello Lammps users,
Hi am using Cu system considering different set of planes.
I have taken z as periodic boundary.

lattice fcc 3.6323
# Simulation box

region s_box block 0 450 0 200 -90.8075 90.8075 units box

Z is given dimension as integral multiple of lattice constant.

Now for different planes, at the periodic boundary (Z-axis), atoms are getting distorted except for z plane as 001

lattice fcc 3.6323 orient x 1 1 0 orient y -1 1 0 orient z 0 0 1 — No distortion
lattice fcc 3.6323 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1 ---- No distortion

lattice fcc 3.6323 orient x 1 -1 0 orient y 1 1 1 orient z -1 -1 2 ----- Distortion

lattice fcc 3.6323 orient x -1 1 0 orient y 0 0 1 orient z 1 1 0 ----- Distortion

lattice fcc 3.6323 orient x 1 0 0 orient y 0 1 -1 orient z 0 1 1 ----Distortion

Figures are also attached after carrying out CNA. Kindly provide some solution to avoid mismatch of atoms with periodic images.

110[001]andz011.png

-110[110]andz001.png

2

Hello Lammps users,
Hi am using Cu system considering different set of planes.
I have taken z as periodic boundary.

*lattice fcc 3.6323 *

*# Simulation box *
*region s_box block 0 450 0 200 -90.8075 90.8075 units box *

Z is given dimension as integral multiple of lattice constant.

​that is not sufficient. depending on the choice of orientation. you may
need to have a multiple of 2, 3 or more lattice constants to have clean
periodic continuation.

axel.​

3

Thank you Axel for reply.
Right now the z axis is 50 times the lattice constant. the number (90.80752) is also integrally divisible by (23.6323) but not by (3*3.6323) .Which dimension then should be chosen for Z. and on what basis? Pl. throw some light.

Till now I could see that 001 z-plane dimension if integrally divisible by lattice constant, then atoms don’t interfere with periodic images.

4

Thank you Axel for reply.
Right now the z axis is 50 times the lattice constant. the number
(90.8075*2) is also integrally divisible by (2*3.6323) but not by
(3*3.6323) .
Which dimension then should be chosen for Z. and on what basis? Pl. throw
some light.

​please grab a crystallography text book and enlighten yourself. it'll be a
more lasting and helpful experience.

axel.​