[Pw_forum] warning for 176 P63/m structure

[Lo_wan_2005XW]

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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