[Pw_forum] How to set periodic boundary condition

[oulihui666]

Dear pwscf users,
    Recently,I am now doing a large job of 'relax' calculation. The unit cell contains 20 atoms and vacuum. We calculated the Pt(111) surface with pwscf, we use a five-layer slab containing 20 Pt atoms, the atoms in the bottom three layers are fixed, and the others are allowed to relax. During calculation, the atoms in top two layers could not keep the structure of (111) plane, I guess that periodic boundary condition is not setted well, and How to set periodic boundary condition ? and how to set translational symmetry ? This is my coordinate file below, is there any problems ?
 
Thank you very much
Best wishes
Lihui Ou
 
ATOMIC_POSITIONS angstrom

   Pt     -0.000000000    0.000000000   -9.062000000    0  0  0

   Pt     -0.000000000    2.775000000   -9.062000000    0  0  0

   Pt      2.403000000   -1.387000000   -9.062000000    0  0  0

   Pt      2.403000000    1.387000000   -9.062000000    0  0  0

   Pt     -0.000000000   -0.000000000   -2.265000000    1  1  1

   Pt     -0.000000000    2.775000000   -2.265000000    1  1  1

   Pt      2.403000000   -1.387000000   -2.265000000    1  1  1

   Pt      2.403000000    1.387000000   -2.265000000    1  1  1

   Pt      1.602000000    0.000000000   -4.531000000    0  0  0

   Pt      1.602000000    2.775000000   -4.531000000    0  0  0

   Pt      4.005000000   -1.387000000   -4.531000000    0  0  0

   Pt      4.005000000    1.387000000   -4.531000000    0  0  0

   Pt      0.801000000    1.387000000   -6.796000000    0  0  0

   Pt      0.801000000    4.162000000   -6.796000000    0  0  0
 
   Pt      3.204000000    0.000000000   -6.796000000    0  0  0
   
   Pt      3.204000000    2.775000000   -6.796000000    0  0  0

   Pt      0.801000000    1.387000000   -0.000000000    1  1  1

   Pt      0.801000000    4.162000000   -0.000000000    1  1  1

   Pt      3.204000000   -0.000000000   -0.000000000    1  1  1

   Pt      3.204000000    2.775000000   -0.000000000    1  1  1


 
 

--

======================================
Lihui Ou
PH.D Candidate in Electrochemistry                      
College of Chemistry and Molecular Science            
Wuhan University,430072,Hubei Province,China 
E-mail:oulihui666 at 126.com
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