[QE-users] Structure with symmetry

Fri Mar 19 12:08:34 CET 2021

> > The last line says: "Symmetry operations form a group”.
> > Great, which group is it?
> >
> >
>
>
>

It should be written on output if you use verbosity="high"
--
Lorenzo Paulatto - Paris
On Mar 19 2021, at 11:48 am, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
> On Fri, Mar 19, 2021 at 11:05 AM Offermans Willem <willem.offermans at vito.be (https://link.getmailspring.com/link/1B9D9B5B-61DC-4C77-A889-E2911CD461A6@getmailspring.com/0?redirect=mailto%3Awillem.offermans%40vito.be&recipient=dXNlcnNAbGlzdHMucXVhbnR1bS1lc3ByZXNzby5vcmc%3D)> wrote:
>
> > The last line says: "Symmetry operations form a group”.
> > Great, which group is it?
> >
> >
>
>
> routine find_symmetry finds only symmetry operations and checkst that they form a group. Which one, it is found later in a different routine. What you prpose (printing the group name where the above message is issued) would require some extensive changes.
>
> Paolo
>
> >
> > 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 (mailto:Willem.Offermans at Vito.be)
> >
> > > On 18 Mar 2021, at 17:39, Lorenzo Paulatto <paulatz at gmail.com (mailto:paulatz at gmail.com)> wrote:
> > > 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 (mailto: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://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Flink.getmailspring.com%2Flink%2F2AD46120-DDAD-4F73-91B7-A26C8881CEA0%40getmailspring.com%2F0%3Fredirect%3Dmailto%253AWillem.Offermans%2540Vito.be%26recipient%3DdXNlcnNAbGlzdHMucXVhbnR1bS1lc3ByZXNzby5vcmc%253D&data=04%7C01%7C%7C0ede0550f7e64c0f1cb908d8ea2c6ed8%7C9e2777ed82374ab992782c144d6f6da3%7C0%7C1%7C637516823855682964%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=Lb1wEO%2FKzG2MuJSR0cu%2BfNjiZOLWaKOa%2F4i%2BkQ6528w%3D&reserved=0)
> > > >
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>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
> _______________________________________________
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