[Wien] is it irrep or is it symmetso that causes the trouble ?
Fecher, Gerhard
fecher at uni-mainz.de
Wed Sep 21 13:38:18 CEST 2016
Dear Peter,
I made a short test for spin polarized iron with SO and 0 0 1 direction,
irrep does not find the correct representations at the Gamma point when starting from the
regular cubic group. It seems, however, that the problem is symmetso which
doesn't find the correct symmetries for the new struct file.
For M along 0 0 1, the coloured point or space group for bcc Fe should be D4h(C4h) or I 4/mm'm', respectively.
(' is the time or spin reversal operator)
(Note that all vertical mirror operations change the sign of the spin and should be removed)
- starting with Oh symmetso finds the 16 operations of D4h instead of the 8 for C4h
(see Koster et al [7], D4h and H along z results in C4h !),
and irrep fails;
- starting from the beginning with C4h, symmetso complains about a missing symmetry
operation in the struct file and writes only the 8 allowed for C4h into the new struct file,
and it seems that irrep succeeds.
Below is some output copied from outputirsoup that shows the effect of the point group symmetry.
I do not know whether or not or how far the not spin polarized cases are also influenced.
I had no time to look into the code, however it seems that a short workarround
would be to stzart already with the correct symmetry in the struct file (may
alternatively be inserted after initializing SO), however, this makes already
fcc Ni with the easy direction of magnetization along 1 1 1 a little
complicated, not to talk about systems with much more atoms, or
antiferroomagnets.
I also realised that in other points of the Brillouin zone C2v, that contains a
vertical mirror operation, remained after symmetso for a ferromagnetic system ??
Here a short result (the final struct files before running the scf with so are attached)
================================================================
starting from space group I m-3m (229)
irrep finds after initializing SO along 0 0 1
knum = 1 kname= 1
k = 0.000000 0.000000 0.000000
The point group is D4h
16 symmetry operations in 10 classes
bnd ndg eigval E 2C4 C2 2C2` 2C2" I 2IC4 IC2 2IC2` 2IC2"
1 1 -3.397181 1.00+0.00i 0.71+0.71i STOP: X=( 0.70711-0.70711) Xold=( 0.70711 0.70711)
4 8 2C4
X not equal for all elements in the class
0.00-1.00i 0.00+0.00i 0.00+0.00i -1.00+0.00i -0.71+0.71i STOP: X=(-0.70711-0.70711) Xold=(-0.70711 0.70711)
1 5 2IC4
X not equal for all elements in the class
0.00+1.00i 0.00+0.00i 0.00+0.00i ??
================================================================
now using from the beginning space group I 4/m (87)
(actually I inserted the 8 symmetry operations of C4h into the struct file (replacing the 48 from Oh))
irrep finds after initializing SO along 0 0 1
(all other parameters of the calculation were identical)
knum = 1 kname= 1
k = 0.000000 0.000000 0.000000
The point group is C4h
8 symmetry operations in 8 classes
bnd ndg eigval E C4 C2 C4- I IC4 IC2 IC4-
1 1 -3.397448 1.00+0.00i 0.71-0.71i 0.00-1.00i 0.71+0.71i -1.00+0.00i -0.71+0.71i 0.00+1.00i -0.71-0.71i =G6-
2 1 -3.364325 1.00+0.00i 0.71+0.71i 0.00+1.00i 0.71-0.71i -1.00+0.00i -0.71-0.71i 0.00-1.00i -0.71+0.71i =G5-
3 ....
!!!! Problem: take care that the symmetry is not changed during initialisation of the calculation !!!!
It would be helpful if the struct file contains the new space group after initializing SO
It would also be helpful if one could use the symmetry operations fixed from the space group
directly, instead of those found by x symmetry (concerns also in2), I wonder whether this would
be possible from x sgroup ?
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 kitahara at phys.mm.t.u-tokyo.ac.jp [kitahara at phys.mm.t.u-tokyo.ac.jp]
Gesendet: Mittwoch, 21. September 2016 03:50
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] irrep error for symmorphic space group
Dear Peter,
If I remember correctly, this problem happens for point group T or Th.
I found this problem several years ago, but I have forgotten it by now.
There was a bug in assignment of class for 3-fold rotations.
Best Regards,
Koichi Kitahara
--
The University of Tokyo, Japan
On Tue, Sep 20, 2016 at 2:41 PM, Fecher, Gerhard <fecher at uni-mainz.de> wrote:
> Dear Peter,
> I tested recently and found that irrep fails mostly (>99%) for magnetic systems with spin-orbit interaction
> (easyiest test cases are simple bcc iron, or fcc nickel)
> it seems it does not correctly detect the magnetic symmetries, I have actually not enough time for more tests, unfortunately.
>
> 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: Dienstag, 20. September 2016 10:34
> An: A Mailing list for WIEN2k users
> Betreff: Re: [Wien] irrep error for symmorphic space group
>
> As far as I know it happens quite often (but not always) that irrep
> fails for spin-orbit calculations.
>
> I'm pretty sure that SO symmetry has not been implemented fully into
> irrep and this might be the reason for this.
>
> Since irrep is a contributed package by Clas Persson, I cannot help you
> much in this respect. All I can offer: Please send me the corresponding
> struct files and I will collect them as "test cases" when I find
> somebody to look in detail into this problem. But I'm not too
> optimistic, since it requires quite some knowledge and lots of work, but
> gives little "credit".
>
> Regards
>
> On 09/19/2016 04:31 PM, Kefeng Wang wrote:
>> Dear wien2k users and developers,
>>
>>
>>
>> I tried to use irrep to analysis the parity of bands. But I got error
>> saying “trsym:cannot find class” and the outputirso file is following:
>>
>>
>>
>> ********************************************************************************
>>
>>
>>
>>
>>
>> knum = 1 kname= GAMMA
>>
>> k = 0.000000 0.000000 0.000000
>>
>>
>>
>> The point group is Th
>>
>> 24 symmetry operations in 8 classes
>>
>> Table 79 on page 86 in Koster et al [7]
>>
>> Table 72.4 on page 633 in Altmann et al [8]
>>
>>
>>
>> E 3C2 4C3 4C3- I 3IC2 4IC3
>> 4IC3-
>>
>> G1+ Ag 1 1 1 1 1 1 1 1
>>
>> G2+ 1Eg 1 1 e e* 1 1 e e*
>>
>> G3+ 2Eg 1 1 e* e 1 1 e* e
>>
>> G4+ Tg 3 -1 0 0 3 -1 0 0
>>
>> G1- Au 1 1 1 1 -1 -1 -1 -1
>>
>> G2- 1Eu 1 1 e e* -1 -1 -e -e*
>>
>> G3- 2Eu 1 1 e* e -1 -1 -e* -e
>>
>> G4- Tu 3 -1 0 0 -3 1 0 0
>>
>> --------------------------------------------------------
>>
>> G5+ E1/2g 2 0 1 1 2 0 1 1
>>
>> G6+ 1F3/2g 2 0 e e* 2 0 e e*
>>
>> G7+ 2F3/2g 2 0 e* e 2 0 e* e
>>
>> G5- E1/2u 2 0 1 1 -2 0 -1 -1
>>
>> G6- 1F3/2u 2 0 e e* -2 0 -e -e*
>>
>> G7- 2F3/2u 2 0 e* e -2 0 -e* -e
>>
>> e=exp(2pi*i/3)
>>
>>
>>
>> labeling of IRs can change due to choice of
>>
>> symmetry axes: G2 <;->; G3 and G6 <;->; G7
>>
>>
>>
>>
>>
>> class, symmetry ops, exp(-i*k*taui)
>>
>> E 21 (+1.00+0.00i)
>>
>> 3C2 1 13 18 (+1.00+0.00i)
>>
>> 4C3 2 3 14 15 16 17 19 20 (+1.00+0.00i)
>> (+1.00+0.00i)
>>
>> I 4 (+1.00+0.00i)
>>
>> 3IC2 7 12 24 (+1.00+0.00i)
>>
>> 4IC3 5 6 8 9 10 11 22 23 (+1.00+0.00i)
>> (+1.00+0.00i)
>>
>>
>>
>> bnd ndg eigval E 3C2 4C3 trsym:cannot find class
>>
>>
>>
>>
>>
>> I went through the archive, and found this usually happens in the case
>> of the k point in the BZ surface of nonsymmorphic space group. But my
>> structure have 204 Im-3 space group and is symmorphic as indicated by x
>> symmetry. Also I was trying to analysis the GAMMA point which is the
>> center of BZ. But I do found that the k point which is not special point
>> works well with irrep. Another point is there are several exponential in
>> the table above instead of simple value. Could anyone tell me what’s the
>> reason of this error?
>>
>>
>>
>> Thanks a lot for your effort in advance.
>>
>>
>>
>> Best
>>
>> Kefeng Wang
>>
>>
>>
>> _______________________________________________
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>>
>
> --
>
> P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
> WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php
> --------------------------------------------------------------------------
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