[QE-users] Structure with symmetry

[Lorenzo Paulatto]

Oddly enoughm the scan_ibrav.x little program does not work in your case (I'm fixing it), but cell2ibrav does:
$ PW/tools/cell2ibrav.x
Enter the lattice vectors (one per line)
1.000000 0.000000 0.000000
0.000000 1.500000 0.000000
0.000000 0.000000 4.596194
Enter alat (or 'x' to skip if axis are in bohr)
10.627880
ibrav = 8
celldm(1) = 10.62788000
celldm(2) = 1.50000000
celldm(3) = 4.59619400
New lattice vectors in bohr:
10.62788000 0.00000000 0.00000000
0.00000000 15.94182000 0.00000000
0.00000000 0.00000000 48.84779829
New lattice vectors in old alat:
1.00000000 0.00000000 0.00000000
0.00000000 1.50000000 0.00000000
0.00000000 0.00000000 4.59619400
New lattice vectors in new alat:
1.00000000 0.00000000 0.00000000
0.00000000 1.50000000 0.00000000
0.00000000 0.00000000 4.59619400
Discrepancy old/new in bohr = 0.000000

--
Lorenzo Paulatto - Paris
On Mar 18 2021, at 10:03 am, Offermans Willem <willem.offermans at vito.be> wrote:
>
> 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 (https://link.getmailspring.com/link/2AD46120-DDAD-4F73-91B7-A26C8881CEA0@getmailspring.com/0?redirect=mailto%3AWillem.Offermans%40Vito.be&recipient=dXNlcnNAbGlzdHMucXVhbnR1bS1lc3ByZXNzby5vcmc%3D)
>
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