[QE-users] Structure with symmetry

[Offermans Willem]

Dear Quantum Espresso friends,

In most of my calculations, I’m dealing with metallic slabs, representing
surfaces, derived from fcc metals, such as (221) or (533).

In these calculations, I’m dealing with structures with symmetry.
The single symmetry element is an inversion center. S_2 is the Schönfließ symbol,
if I recall correctly. 

In the output file of pw.x, I encounter the following note:

<snip>
...
     Message from routine setup:
     using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead
…
</snip>

The unitcell is defined as:

<snip>
...
     celldm(1)=  10.627880  celldm(2)=   0.000000  celldm(3)=   0.000000
     celldm(4)=   0.000000  celldm(5)=   0.000000  celldm(6)=   0.000000

     crystal axes: (cart. coord. in units of alat)
               a(1) = (   1.000000   0.000000   0.000000 )  
               a(2) = (   0.000000   1.500000   0.000000 )  
               a(3) = (   0.000000   0.000000   4.596194 )  
…
</snip>

I would like to follow the advice to use the correct ibrav, but I need some help
to determine the correct ibrav. 

Can someone help me to determine the correct Ibrav?





Met vriendelijke groeten,
Mit freundlichen Grüßen,
With kind regards,


Willem Offermans
Researcher Electrocatalysis SCT
VITO NV | Boeretang 200 | 2400 Mol
Phone:+32(0)14335263 Mobile:+32(0)492182073 

Willem.Offermans at Vito.be



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