[Wien] initso and symmetso (NO inversion symmetry)/ too high symmetry

Fecher, Gerhard fecher at uni-mainz.de
Thu Dec 1 08:06:36 CET 2016 

The symmetry of P 2_1 3 (198) is (for example for the FeSi (cP8) structure) reduced to the coloured groups as follows (' =  (time inv.))
0 0 1 ==> P 2_1' 2_1' 2_1 (19.27)   (4 Sym. Ops.)   
1 1 1 ==> R 3 (146.10)  (3 Sym Ops.)
These are just the numbers of symmetry operations you find with symmetso
therfore, I don't think that there is any bug.

you should find in case.outsymso something like

  symmetry operation           3
   1   0   0
   0   1   0
   0   0   1
  operation type A preserve M direction

  symmetry operation           4
   0  -1   0
   0   0  -1
   1   0   0
  operation type C does not preserve M direction

  symmetry operation          11
  -1   0   0
   0   1   0
   0   0  -1
  operation type B *(time inv.) preserve M direction

  ....

that tells you which operation is allowed and which not, and thus which one is kept and which not.
Overall it seems that the program is more clever than the manual ;-)

***** Hmm, it would be interesting if the correct coloured group (number) is written into the structure file after initso_lapw *****



PS.: (time inv.) is sometimes called the "spin reversal operator" that hits better what it is doing.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von "Niedermayr, Arthur" [a.niedermayr at protonmail.com]
Gesendet: Mittwoch, 30. November 2016 22:00
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] initso and symmetso (NO inversion symmetry)/ too high symmetry

Hello wienusers,
thank you all for your thoughts!

@ Mr. Nestoklon: Thank you, I will for sure try your solution.
@ Mr. Fecher: Sorry that I didn't mention it,


I got the too-high-symmetry issue, when I exactly did what you said: (all in w2web)
1) scf without spin orbit
2) initso_lapw in w2web
3) rerun scf with spin orbit.
For the 0 0 1 (h k l) axis, I got a four-fold symmetry (amongst others there are 2 B symmetry options (mirror planes)); in this case (= 001) only 2 symmetry operations should remain.
A magnetisation axis in 001 for the P213 group should definitely have a lower symmetry than in 111 (in 111 direction you said that there should remain 3 options)
What did you actually mean by saying: <<The details of the symmetry operations and which HAVE TO BE REMOVED should all be in the output of symmetso>>? Do I have to remove them manually?
@ Mr. Blaha: As far as I know  <<spin-orbit does not break time-inversion symmetry and these B-symops times time-inversion are still valid operations>> isn't true  for the group P213. Please correct me if I am wrong :)


Best regards
Arthur Niedermayr

Ps: using wien2k 14.2, all patches are installed.

-------- Original Message --------
Subject: Re: [Wien] initso and symmetso (NO inversion symmetry)/ too high symmetry
Local Time: 30. November 2016 7:11 PM
UTC Time: 30. November 2016 18:11
From: fecher at uni-mainz.de
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>

I did recently calculations for that space group with SO for spinpolarized cases.
The details of the symmetry operations and which have to be removed should all be in the output of symmetso
I had no problems
Maybe you wish to use 1 1 1 for the quantisation axis, in that case only three operations should remain
(I used both 0 0 1 and 1 1 1)

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von Peter Blaha [pblaha at theochem.tuwien.ac.at]
Gesendet: Mittwoch, 30. November 2016 17:55
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] initso and symmetso (NO inversion symmetry)/ too high symmetry

As far as I know, initso (in a spin-polarized case) is supposed to
create case.ksym anyway, so there is no need do this copying ??

Or is there a bug in (recent) initso ??

On 11/30/2016 03:00 PM, Mikhail Nestoklon wrote:
>
> To avoid this behavior (which, I believe, is a bug) and DO NOT assume
> inversion if it does not exist in the structure I do the following:
> AFTER initso_lapw I copy original structure with the proper symmetry to
> the one which is used in k generation
> $ cp *.struct *.ksym
> After this, rerun the k generation by
> $ x kgen -so
> and then proceed as usual.
>
> Sincerely.
> Mikhail.
>
>
>
> Hello wienusers,
>
>
> I wanted to do a scf calculation (*WITH spin-orbit interaction*) in
> a *spin polarize*d system *WITHOUT inversion symmetry* (space group
> P213).
> But I have a problem with the symmetry options:
>
> According to the manual
> /<<Depending on the presence of inversion symmetry it will keep
> (inversion is present) or remove the B-type operations.>> (in the
> beginning of chapter 9)/
> there shouldn't be B-type operations, but in the **.ksym* / *.klist
> /**struct_so* file I have a too high symmetry and the B-type
> symmetry operations are still there.
>
> I also don't understand what is meant with this steatment:
>
> /<<If you don’t have inversion symmetry in the original structure,
> you must not “add inversion”in KGEN.>> (chapter 4.5.5)/
>
> _How can I kill the B-type symmetry operations? Is it possible to do
> that via the w2web environment or do I have to edit some ksym or
> struct files manually?_
>
>
> Best regards
> Arthur Niedermayr
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--

P.Blaha
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