command of cna/atom

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1

Hello everyone,

I use the command ‘compute 1 all cna/atom 3.0855’ to observe the local
structure of my model. But I find the data of initial structure I build in
output file are not ‘1’ which means fcc, there are a lot of ‘5’ means
unknown. Are there any errors in my in file code?

2

Hello everyone,

I use the command 'compute 1 all cna/atom 3.0855' to observe the local
structure of my model. But I find the data of initial structure I build in
output file are not '1' which means fcc, there are a lot of '5' means
unknown. Are there any errors in my in file code?
*******************************
part of my in file code is as follow:
units metal
  boundary p p p

  atom_style atomic

lattice fcc 3.6147
region whole block 0.0 10.0 0.0 10.0 0.0 10.0 units box
create_box 1 whole
create_atoms 1 region whole
**********************************
Furthermore, if I delete 'units box', which means the unit is based on
lattice. The new initial structure checked by cna/atom command is right!
All are fcc=1!

yes, this makes perfect sense. at 10 angstrom edge length,
your box and region is not commensurate with your fcc lattice
spacing and thus you have mismatches at the periodic boundaries
resulting in an "unknown" coordination.

Then I'd like to build a coherent twin boundary in the middle of my cube
model. Combine the left and right part. As below:

***********************************
# the whole box
lattice fcc 3.6147
region whole block 0.0 10.0 0.0 10.0 0.0 10.0
create_box 1 whole
create_atoms 1 region whole

# left part
region left block 0.0 5.0 INF INF INF INF
lattice fcc 3.6147 orient x -1 1 -1 orient y -1 1 2 orient z 1 1 0
create_atoms 1 region left

# right part
region right block 5.0 10.0 INF INF INF INF
lattice fcc 3.6147 orient x 1 -1 1 orient y -1 1 2 orient z -1 -1 0
create_atoms 1 region right

# delete overlap atoms
delete_atoms overlap 0.275 left right
*******************************************************
Based on the code I write above, I cannot obtain the model I want. I don't
know why?

first you fill the *entire* box with atoms, *then* you
place a set of atoms on the left and on the right
half. that makes no sense. why the first create_atoms??

axel.