[Pw_forum] warning for 176 P63/m structure

[Stefano de Gironcoli]

Dear Xiangang Wan,
there is a section in the manual and a few thousand posts in the mailing
list archive
explaining this issue.
best,

Stefano de Gironcoli - SISSA and DEMOCRITOS


thereOn 08/17/2011 08:23 AM, Lo_wan_2005XW wrote:
> Dear all,
>
> I am studying a compound with P63/m structure.
>
> But the program complain:
>
>      warning: symmetry operation #  2 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>      warning: symmetry operation #  5 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>      warning: symmetry operation #  6 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>      warning: symmetry operation # 14 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>      warning: symmetry operation # 17 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>      warning: symmetry operation # 18 not allowed.   fractional translation:
>        0.0000000  0.0000000  0.5000000  in crystal coordinates
>
>
> Our compound has P63/m structure (176 space group). And following is the setup:
>
> --------------------------------------------
>  &system
>     ibrav=  4, celldm(1) =10.726090,
>     celldm(3)=1.25440, nat=  12, ntyp= 2, ecutwfc =35.0,ecutrho=300
>     occupations='smearing', smearing='marzari-vanderbilt', degauss=0.05
>  /
>  &electrons
>     diagonalization='david'
>     mixing_beta = 0.7
>  /
> ATOMIC_SPECIES
>  La 138.9055 La.pbe-n-bpaw.UPF
>  Si 28.0855  Si.pbe-n-van.UPF
> ATOMIC_POSITIONS crystal
> La 0.00000000  0.00000000  0.50000000
> La 0.00000000  0.00000000  0.00000000
> Si 0.48000000  0.99000000  0.75000000
> Si 0.01000000  0.49000000  0.75000000
> Si 0.51000000  0.52000000  0.75000000
> Si 0.52000000  0.01000000  0.25000000
> Si 0.99000000  0.51000000  0.25000000
> Si 0.49000000  0.48000000  0.25000000
> Si 0.333333333 0.666666666 0.50000000
> Si 0.666666666 0.333333333 0.00000000
> Si 0.666666666 0.333333333 0.50000000
> Si 0.333333333 0.666666666 0.00000000
> K_POINTS automatic
> 6 6 5 0 0 0
> --------------------------------------------
>
> Following is "atomic positions are in cartesian coordinates" printed by the program
>
>      site n.     atom                  positions (alat units)
>          1           La  tau(   1) = (   0.0000000   0.0000000   0.6272000  )
>          2           La  tau(   2) = (   0.0000000   0.0000000   0.0000000  )
>          3           Si  tau(   3) = (  -0.0150000   0.8573651   0.9408000  )
>          4           Si  tau(   4) = (  -0.2350000   0.4243524   0.9408000  )
>          5           Si  tau(   5) = (   0.2500000   0.4503332   0.9408000  )
>          6           Si  tau(   6) = (   0.5150000   0.0086603   0.3136000  )
>          7           Si  tau(   7) = (   0.7350000   0.4416730   0.3136000  )
>          8           Si  tau(   8) = (   0.2500000   0.4156922   0.3136000  )
>          9           Si  tau(   9) = (   0.0000000   0.5773503   0.6272000  )
>         10           Si  tau(  10) = (   0.5000000   0.2886751   0.0000000  )
>         11           Si  tau(  11) = (   0.5000000   0.2886751   0.6272000  )
>         12           Si  tau(  12) = (   0.0000000   0.5773503   0.0000000  )
>
>
> I cannot find any error in the setup. So why there is a warning about the symmetry operation? Does it serious problem?
>
> Thanks
>
> Xiangang Wan
> Department of Physics
> Nanjing University
>  		 	   		  
>
>
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