[Pw_forum] How to set periodic boundary condition

[Stefano de Gironcoli]

The code enforce periodic boundary condition automatically so there must 
be something wrong in your input.
how are oriented your unit cell lattice vectors in space ?
are they compatible with the atomic coordinates you give ?
have you visualized your cell using some visualization tool (like 
XCrysDen) that the cell is what you think it is ?
Hope this help
stefano

oulihui666 wrote:
> 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 3204000000 -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 <mailto:oulihui666 at 126.com>/
> ======================================
>
>
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