[Wien] AFM calculations

[Lawal Mohammed]

Dear respected Developers and Users,

I am trying to understand how to do AFM calculations with SO. I read section 
4.5.4 of the UG and check some threads in the wien list. 
The way I understand it, one can choose either of the two options.

 1-run runsp_lapw and then do scf with SO
OR
2-runafm_lapw and then do SO
 I may probably be wrong. I want to test run with Fe2O3.

Any advice is highly appreciated.

Regards

Lawal 




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[Wien] AFM Calculations

[Murugan Sundareswari]

Dear Wien2k Users,

I have been trying my hand at AFM Calculations.

We were able to run spin polarized calculations and when we landed at the
AFM calculation, we got the following output:

 case.struct_supergroup present
 The super and subgroups are KLASSENGLEICH
 You must specify a translation vector which transforms the
 spin-up into the spin-dn atom (e.g.: 0.5,0.5,0.5 for AFM bcc
Cr)!*rrot not found*
0.001u 0.001s 0:00.00 0.0%  0+0k 0+8io 0pf+0w


Since we did not realize what this rrot was, we continued looking into
case.outputafminput where we found

FILE OPENED SUCCESSFULLY: dypdbi-afm.outputafm
FILE OPENED SUCCESSFULLY: dypdbi-afm.inclmcopy
FILE OPENED SUCCESSFULLY: dypdbi-afm.clmup
FILE OPENED SUCCESSFULLY: dypdbi-afm.clmdn
FILE OPENED SUCCESSFULLY: dypdbi-afm.struct
FILE OPENED SUCCESSFULLY: dypdbi-afm.struct_su

NUMBER OF ATOMS:   3
.
.
.
.
and at the end we saw
" equivalent position not found  0.000E+000
0.000E+000
  0.000E+000  0.7501.25
  0.250

Could some one help me understand my miss please?
Regards
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[Wien] afm calculations

[mahshid hezary]

Dear Wien Users,
I am a new user and doing some calculation about afm. I have read the UG and 
FAQ and searching ML. it seems to me that there is not enough? information 
about afm calculations. Could anyone please give me the responce of the 
following Qs. or show? me a reference for more study?
1- what is the? criteria for making a? case.struct _supergroup in general? 
2-how to find the proper symetry operation matrices for any case if we are not 
able to find the prper supergroup?
3-what is the forth column in the symetry operation matrice which has been used 
in UG for bcc Cr ( i. e. 0.50 0.5 0.5)?
?Regards,
M. Hezary,




  
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[Wien] afm calculations

[Peter Blaha]

If you do not understand the Cr example, than forget about the runafm option.

Do a normal spin-polarized calculation (runsp), but still, do not forget to 
"flip"
the spin of the AFM atoms during init. The newinstgen -askallows this 
to do easily.

mahshid hezary schrieb:
> Dear Wien Users,
> I am a new user and doing some calculation about afm. I have read the UG 
> and FAQ and searching ML. it seems to me that there is not enough  
> information about afm calculations. Could anyone please give me the 
> responce of the following Qs. or show  me a reference for more study?
> 1- what is the  criteria for making a  case.struct _supergroup in general?
> 2-how to find the proper symetry operation matrices for any case if we 
> are not able to find the prper supergroup?
> 3-what is the forth column in the symetry operation matrice which has 
> been used in UG for bcc Cr ( i. e. 0.50 0.5 0.5)?
>  Regards,
> M. Hezary,
> 
> 
> 
> 
> 
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Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
-

Re: [Wien] AFM calculations

[Peter Blaha]

Without SO: You can either use runafm (if you can figure out the correct 
symmetry operation which transforms spin-up into spin-dn atoms) OR 
runsp_lapw (takes twice as much cpu time, but is "simpler").


With SO you must use runsp. runafm does not support spin-orbit.


Am 20.04.2018 um 13:24 schrieb Lawal Mohammed:

Dear respected Developers and Users,

I am trying to understand how to do AFM calculations with SO. I read 
section 4.5.4 of the UG and check some threads in the wien list.


The way I understand it, one can choose either of the two options.

1-run runsp_lapw and then do scf with SO

OR

2-runafm_lapw and then do SO

I may probably be wrong. I want to test run with Fe2O3.

Any advice is highly appreciated.

Regards

*/Lawal
/*





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Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
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Re: [Wien] AFM calculations

[Lawal Mohammed]

Dear Prof. Peter,

Thanks a lot for the explanation. I have another question in this regard.
Please why do we have to do spin-polarized calculation for O2 (or for 
non-closed shell elements) as mentioned in the FAQ page under  Calculations of 
cohesive or formation energies?

Thanks very much for your time.

Kind regards.

Lawal 




 

On Monday, April 23, 2018, 1:10:32 PM GMT+8, Peter Blaha 
 wrote:  
 
 Without SO: You can either use runafm (if you can figure out the correct 
symmetry operation which transforms spin-up into spin-dn atoms) OR 
runsp_lapw (takes twice as much cpu time, but is "simpler").

With SO you must use runsp. runafm does not support spin-orbit.


Am 20.04.2018 um 13:24 schrieb Lawal Mohammed:
> Dear respected Developers and Users,
> 
> I am trying to understand how to do AFM calculations with SO. I read 
> section 4.5.4 of the UG and check some threads in the wien list.
> 
> The way I understand it, one can choose either of the two options.
> 
> 1-run runsp_lapw and then do scf with SO
> 
> OR
> 
> 2-runafm_lapw and then do SO
> 
> I may probably be wrong. I want to test run with Fe2O3.
> 
> Any advice is highly appreciated.
> 
> Regards
> 
> */Lawal
> /*
> 
> 
> 
> 
> 
> ___
> Wien mailing list
> Wien@zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
> 

-- 
--
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Phone: +43-1-58801-165300            FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW: 
http://www.imc.tuwien.ac.at/tc_blaha-
 

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Re: [Wien] AFM calculations

[Peter Blaha]

Because for cohesive energies you need the ground state energies of the 
atoms/molecules involved.


And the ground state of O2 has 2 unpaired electrons, i.e. it requeres a 
spin polarized calculation.


Test it yourself: Do a spin and non-spinpolarized calculationfor O2 (in 
2 directories) with otherwise identical parameters. Which energy is lower ?


Am 24.04.2018 um 05:19 schrieb Lawal Mohammed:

Dear Prof. Peter,

Thanks a lot for the explanation. I have another question in this regard.
Please why do we have to do spin-polarized calculation for O2 *(or for 
non-closed shell elements)* as mentioned in the FAQ page under 
*Calculations of cohesive or formation energies 
*?


Thanks very much for your time.

Kind regards.

*/Lawal
/*





On Monday, April 23, 2018, 1:10:32 PM GMT+8, Peter Blaha 
 wrote:



Without SO: You can either use runafm (if you can figure out the correct
symmetry operation which transforms spin-up into spin-dn atoms) OR
runsp_lapw (takes twice as much cpu time, but is "simpler").

With SO you must use runsp. runafm does not support spin-orbit.


Am 20.04.2018 um 13:24 schrieb Lawal Mohammed:
 > Dear respected Developers and Users,
 >
 > I am trying to understand how to do AFM calculations with SO. I read
 > section 4.5.4 of the UG and check some threads in the wien list.
 >
 > The way I understand it, one can choose either of the two options.
 >
 > 1-run runsp_lapw and then do scf with SO
 >
 > OR
 >
 > 2-runafm_lapw and then do SO
 >
 > I may probably be wrong. I want to test run with Fe2O3.
 >
 > Any advice is highly appreciated.
 >
 > Regards
 >
 > */Lawal

 > /*
 >
 >
 >
 >
 >
 > ___
 > Wien mailing list
 > Wien@zeus.theochem.tuwien.ac.at 
 > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
 > SEARCH the MAILING-LIST at: 
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html

 >

--
--
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300            FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at   
   WIEN2k: http://www.wien2k.at

WWW:
http://www.imc.tuwien.ac.at/tc_blaha- 



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--
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Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
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http://www.imc.tuwien.ac.at/tc_blaha- 


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Re: [Wien] AFM calculations

[Lawal Mohammed]

Thanks a lot Prof. Peter.

I run a test case with O2, I got a difference of about 0.04Ry. With sp 
calculations having the lower energy.

Regards
 
Lawal 

 

On Tuesday, April 24, 2018, 1:36:29 PM GMT+8, Peter Blaha 
 wrote:  
 
 This message is eligible for Automatic Cleanup! (pbl...@theochem.tuwien.ac.at) 
Add cleanup rule | More info
 Because for cohesive energies you need the ground state energies of the 
atoms/molecules involved.

And the ground state of O2 has 2 unpaired electrons, i.e. it requeres a 
spin polarized calculation.

Test it yourself: Do a spin and non-spinpolarized calculationfor O2 (in 
2 directories) with otherwise identical parameters. Which energy is lower ?

Am 24.04.2018 um 05:19 schrieb Lawal Mohammed:
> Dear Prof. Peter,
> 
> Thanks a lot for the explanation. I have another question in this regard.
> Please why do we have to do spin-polarized calculation for O2 *(or for 
> non-closed shell elements)* as mentioned in the FAQ page under 
> *Calculations of cohesive or formation energies 
> *?
> 
> Thanks very much for your time.
> 
> Kind regards.
> 
> */Lawal
> /*
> 
> 
> 
> 
> 
> On Monday, April 23, 2018, 1:10:32 PM GMT+8, Peter Blaha 
>  wrote:
> 
> 
> Without SO: You can either use runafm (if you can figure out the correct
> symmetry operation which transforms spin-up into spin-dn atoms) OR
> runsp_lapw (takes twice as much cpu time, but is "simpler").
> 
> With SO you must use runsp. runafm does not support spin-orbit.
> 
> 
> Am 20.04.2018 um 13:24 schrieb Lawal Mohammed:
>  > Dear respected Developers and Users,
>  >
>  > I am trying to understand how to do AFM calculations with SO. I read
>  > section 4.5.4 of the UG and check some threads in the wien list.
>  >
>  > The way I understand it, one can choose either of the two options.
>  >
>  > 1-run runsp_lapw and then do scf with SO
>  >
>  > OR
>  >
>  > 2-runafm_lapw and then do SO
>  >
>  > I may probably be wrong. I want to test run with Fe2O3.
>  >
>  > Any advice is highly appreciated.
>  >
>  > Regards
>  >
>  > */Lawal
> 
>  > /*
>  >
>  >
>  >
>  >
>  >
>  > ___
>  > Wien mailing list
>  > Wien@zeus.theochem.tuwien.ac.at 
>  > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>  > SEARCH the MAILING-LIST at: 
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>  >
> 
> -- 
> --
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300            FAX: +43-1-58801-165982
> Email: bl...@theochem.tuwien.ac.at   
>    WIEN2k: http://www.wien2k.at
> WWW:
> http://www.imc.tuwien.ac.at/tc_blaha-
>  
> 
> 
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> 
> 
> 
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Phone: +43-1-58801-165300            FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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[Wien] AFM calculations for YBCO6

[Madesis Ioannis(John)]

Good evening everyone

I am having trouble with the struct file for these calculations. To be 
more specific: This material has 2 nonequivalent Cu atoms, Cu1 and Cu2. 
Each one of these sits at the four corners of the unit cell, Cu1 at z=0 
and Cu2 at approximately z=1/3, and the space group is 123.
In order to achieve AFM ordering, I need to have 2 types of Cu1, and the 
spacegroup doesn't let me do that. Once I place Cu1(up), all 4 corners 
have Cu1(up). What can I do to solve this?


--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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Re: [Wien] AFM calculations for YBCO6

[pieper]

Good eveneing, Ioannis Madesis

As you observed yourself: The (primitve) unit cell of your structure 
does not have enough Cu1 to support AFM on that sublattice. For that you 
need at least two Cu1 atoms. You achieve that by doubling (at least) the 
unit cell (perhaps using supercell) and assigning two different numbers 
to the Cu-sites you want to assign opposite spins to. As far as I recall 
you should double the unit cell along the a- AND the b-axis to be able 
to assign the correct spin directions. If you want to describe AF 
stacking sequences along the c-axis you will have to double the unit 
cell along that axis. Once you assigned numbers to Cu according to their 
two spin directions in your supercell (say, leave Cu1 for up, rename the 
Cu1 you want to point down into Cu3) you can let nn and symmetry do the 
job of finding the corresponding space group - which will necessarily be 
different from 123 (consult the UG for this procedure).


Good luck

Martin Pieper


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 15.05.2015 14:32, schrieb Madesis Ioannis(John):

Good evening everyone

I am having trouble with the struct file for these calculations. To be
more specific: This material has 2 nonequivalent Cu atoms, Cu1 and
Cu2. Each one of these sits at the four corners of the unit cell, Cu1
at z=0 and Cu2 at approximately z=1/3, and the space group is 123.
In order to achieve AFM ordering, I need to have 2 types of Cu1, and
the spacegroup doesn't let me do that. Once I place Cu1(up), all 4
corners have Cu1(up). What can I do to solve this?

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Re: [Wien] AFM calculations for YBCO6

[delamora]

What magnetic ordering do you have?
If Cu1 is up and Cu2 is dn then you have to calculate it with this ordering!
For an afm calculation you need a symmetry operation that moves Cu1 to Cu2.
In that case you do an afm calculation with runafm, otherwise you assign Cu1 as 
up and Cu2 as dn and do a runsp calculation.
There is another issue, if you have a symmetry operation that moves Cu1 to Cu2 
then the primitive cell probably has only one Cu (I mean, for a simple system)
Cr is the example, Cr has B symmetry, and has one Cr. To make the afm 
calculation then you change to P symmetry with two Cr and assign one as up and 
the other as dn.
One interesting exception is the rutile symmetry, where there is an M atom at 
0,0,0 and another at 1/2,1/2,1/2, but to go from one to the other you need;
0 -1 0  0.5
1 0 0   0.5
0 0 1   0.5
that is, a rotation by 90 degrees in the 001 axis.

Pablo

De: wien-boun...@zeus.theochem.tuwien.ac.at 
 en nombre de pieper 

Enviado: viernes, 15 de mayo de 2015 08:28 a. m.
Para: A Mailing list for WIEN2k users
Asunto: Re: [Wien] AFM calculations for YBCO6

Good eveneing, Ioannis Madesis

As you observed yourself: The (primitve) unit cell of your structure
does not have enough Cu1 to support AFM on that sublattice. For that you
need at least two Cu1 atoms. You achieve that by doubling (at least) the
unit cell (perhaps using supercell) and assigning two different numbers
to the Cu-sites you want to assign opposite spins to. As far as I recall
you should double the unit cell along the a- AND the b-axis to be able
to assign the correct spin directions. If you want to describe AF
stacking sequences along the c-axis you will have to double the unit
cell along that axis. Once you assigned numbers to Cu according to their
two spin directions in your supercell (say, leave Cu1 for up, rename the
Cu1 you want to point down into Cu3) you can let nn and symmetry do the
job of finding the corresponding space group - which will necessarily be
different from 123 (consult the UG for this procedure).

Good luck

Martin Pieper


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 15.05.2015 14:32, schrieb Madesis Ioannis(John):
> Good evening everyone
>
> I am having trouble with the struct file for these calculations. To be
> more specific: This material has 2 nonequivalent Cu atoms, Cu1 and
> Cu2. Each one of these sits at the four corners of the unit cell, Cu1
> at z=0 and Cu2 at approximately z=1/3, and the space group is 123.
> In order to achieve AFM ordering, I need to have 2 types of Cu1, and
> the spacegroup doesn't let me do that. Once I place Cu1(up), all 4
> corners have Cu1(up). What can I do to solve this?
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Re: [Wien] AFM calculations for YBCO6

[delamora]

Hi John,
You have the famous 1236 derived from the more famous 1237
In here you have one plane of Cu1 and two of Cu2
What order would you expect?
Cu1 are quite far away so there would be no strong correlation between them.
On the other hand Cu2 have O connecting them in the plane, so you would expect 
an inplane antiferromagnetic ordering.
>From your question it seems that you already knew this, but you did not make 
>it clear.
So you need two kind of Cu in the same plane in alternating magnetic 
directions, like 001 plane in NaCl, Na alternates with Cl
So you make a 2 2 1 supercell
Mark Cu in 000 and 1/2 1/2 0 as Cu1 
and 1/2 0 0 and 0 1/2 0 as Cu2
and erase the number in all other atoms
Then the program choose a simpler cell with the same symmetry, and you put with 
"instgen" alternating spins, up and dn, for Cu and n for all others
The afm operation is
100 .5
010 .5
001 0
I did the calculation and MM converges to 0, so you need the Hubbard U

De: wien-boun...@zeus.theochem.tuwien.ac.at 
 en nombre de delamora 

Enviado: viernes, 15 de mayo de 2015 04:03 p. m.
Para: A Mailing list for WIEN2k users
Asunto: Re: [Wien] AFM calculations for YBCO6

What magnetic ordering do you have?
If Cu1 is up and Cu2 is dn then you have to calculate it with this ordering!
For an afm calculation you need a symmetry operation that moves Cu1 to Cu2.
In that case you do an afm calculation with runafm, otherwise you assign Cu1 as 
up and Cu2 as dn and do a runsp calculation.
There is another issue, if you have a symmetry operation that moves Cu1 to Cu2 
then the primitive cell probably has only one Cu (I mean, for a simple system)
Cr is the example, Cr has B symmetry, and has one Cr. To make the afm 
calculation then you change to P symmetry with two Cr and assign one as up and 
the other as dn.
One interesting exception is the rutile symmetry, where there is an M atom at 
0,0,0 and another at 1/2,1/2,1/2, but to go from one to the other you need;
0 -1 0  0.5
1 0 0   0.5
0 0 1   0.5
that is, a rotation by 90 degrees in the 001 axis.

Pablo

De: wien-boun...@zeus.theochem.tuwien.ac.at 
 en nombre de pieper 

Enviado: viernes, 15 de mayo de 2015 08:28 a. m.
Para: A Mailing list for WIEN2k users
Asunto: Re: [Wien] AFM calculations for YBCO6

Good eveneing, Ioannis Madesis

As you observed yourself: The (primitve) unit cell of your structure
does not have enough Cu1 to support AFM on that sublattice. For that you
need at least two Cu1 atoms. You achieve that by doubling (at least) the
unit cell (perhaps using supercell) and assigning two different numbers
to the Cu-sites you want to assign opposite spins to. As far as I recall
you should double the unit cell along the a- AND the b-axis to be able
to assign the correct spin directions. If you want to describe AF
stacking sequences along the c-axis you will have to double the unit
cell along that axis. Once you assigned numbers to Cu according to their
two spin directions in your supercell (say, leave Cu1 for up, rename the
Cu1 you want to point down into Cu3) you can let nn and symmetry do the
job of finding the corresponding space group - which will necessarily be
different from 123 (consult the UG for this procedure).

Good luck

Martin Pieper


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 15.05.2015 14:32, schrieb Madesis Ioannis(John):
> Good evening everyone
>
> I am having trouble with the struct file for these calculations. To be
> more specific: This material has 2 nonequivalent Cu atoms, Cu1 and
> Cu2. Each one of these sits at the four corners of the unit cell, Cu1
> at z=0 and Cu2 at approximately z=1/3, and the space group is 123.
> In order to achieve AFM ordering, I need to have 2 types of Cu1, and
> the spacegroup doesn't let me do that. Once I place Cu1(up), all 4
> corners have Cu1(up). What can I do to solve this?
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Re: [Wien] AFM calculations for YBCO6

[Madesis Ioannis(John)]

Mr. Delamora, first of all thank you for your dedication, and thorough 
examination of my problem.


I haven't fully tested your solution, however, there are plenty of AFM 
orderings that I wish to test such as A, G and C type, all of which are 
different combinations of in-plane antiferromagnetism. From first trials 
of your solution, what troubles me is the fact that the 
case_super.struct file does not include any numbers such as Cu1, O3. 
However, I have noticed that some of the atoms have "MULT= 2" or "MULT= 
4" and present additional 1 or 3 positions. So I thought of the 
following:
Keep the 1 x 1 x 1 cell, for the sake of calculations, and split by 
myself the Cu1 atoms from 1 atom of MULT= 4, to 2 groups of MULT= 2, and 
use your solution of naming appropriately each atom. I know that you 
suggested something particular, and thank you, but I need to keep the 
computational cost low. Last, I change the space group to "1". After I 
do what I said, I run an initialization, and a proper space group is 
defined. How is that for a solution?


--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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Re: [Wien] AFM calculations for YBCO6

[delamora]

This is a problem I had studied before, but non magnetic, so I was curious to 
try the magnetic case; w
With YBa2Cu3O7 you have magnetism and superconductivty! braking one of Matthias 
rules

The result I got for, YBa2Cu3O6, was that Cu1 MM=0.0007 or "non magnetic" as 
far as the calculations show.
Cu2=0.5873 with U=4eV
So, you have to study only Cu2 for magnetism.
From my point of view you the most and I would guess only ordering of the 
inplane spins is like a chess board, alternating un and dn.
the interplanar Cu2-Cu2 ordering can be up-up or up-dn, but since there are no 
oxygen atoms between the planes the difference should be quite small.

I did the calculation with RxK=7 and 100 k-points with 4 parallel cores, it 
took half an hour.

In the supercell output you have to delete all the numbers
Ba 1 => Ba, O 1 => O and only number 1 and 2 the Cu as you want to order them
I did;
Cu 00x and 1/2,1/2,x as Cu 1 and later as 'up'
and for 0,1/2,x and 1/2,0,x as Cu 2 and later as 'dn'
Now you can have 00,-x as 'dn' and 0,1/2,-x as up and this gives another 
ordering

De: wien-boun...@zeus.theochem.tuwien.ac.at 
 en nombre de Madesis Ioannis(John) 

Enviado: sábado, 16 de mayo de 2015 01:09 p. m.
Para: Wien
Asunto: Re: [Wien] AFM calculations for YBCO6

Mr. Delamora, first of all thank you for your dedication, and thorough
examination of my problem.

I haven't fully tested your solution, however, there are plenty of AFM
orderings that I wish to test such as A, G and C type, all of which are
different combinations of in-plane antiferromagnetism. From first trials
of your solution, what troubles me is the fact that the
case_super.struct file does not include any numbers such as Cu1, O3.
However, I have noticed that some of the atoms have "MULT= 2" or "MULT=
4" and present additional 1 or 3 positions. So I thought of the
following:
Keep the 1 x 1 x 1 cell, for the sake of calculations, and split by
myself the Cu1 atoms from 1 atom of MULT= 4, to 2 groups of MULT= 2, and
use your solution of naming appropriately each atom. I know that you
suggested something particular, and thank you, but I need to keep the
computational cost low. Last, I change the space group to "1". After I
do what I said, I run an initialization, and a proper space group is
defined. How is that for a solution?

--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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Re: [Wien] AFM calculations for YBCO6

[Madesis Ioannis(John)]

There is one final matter, I am trying now to solve, but I believe it 
will be solved today:

Your approach results to a C-type antiferromagnetic ordering

http://folk.uio.no/ponniahv/activity/ordering/spinfig.html

which is chessboard like, but every CuO layer is similar to the other. I 
want to achieve a G-type ordering. Chessboard-like again, but 2 
consecutive layers are again, opposite.


I believe this thread has gotten beyond wien2k troubleshooting, I hope I 
don't cause any problems.


--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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Re: [Wien] AFM calculations for YBCO6

[pieper]

Good evening,

Sorry, I commented first without remembering the structure correctly.

The antiferromagnetic and superconducting phase diagram of Y123O(6+x) 
has been studied experimentally very extensively in the 90's with - in 
my opinion - very clear results on the exact AF phases from neutron 
diffraction and NMR. I don't want to drown anyone in literature, so 
being an NMR guy I strongly suggest to look into the NMR work:


E. Brecht and W. W. Schmahl and H. Fuess and S. Schmenn and H. 
L{\"u}tgemeier and N. H. Andersen and B. Lebech and Th. Wolf,
Neutron diffraction and NQR study of the intermediate turn angle phase 
formed during AFI to AFII reordering in 
{YBa$_2$Cu$_{3-x}$Al$_x$O$_{6+\delta}$},

Physical Review B, 1997, 56, no.2, p 940

Allow me to suggest in addition my own work

K. Nehrke and M. W. Pieper and T. Wolf,
Local magnetic properties of PrBa2Cu3O6+x: {NMR} and {NQR} in crystals,
Phys. Rev. B, 1996, 53, 1

Perhaps you can work from there through the references for details and 
additional studies.


There are two crystalografic different Cu sites in the perovskite, the 
so-called chain- and twice as many plane-sites. The variable oxygen 
content is between the Cu chain sites. In accord with what Prof. 
Delamora noted, the Cu on chains never carrys a magnetic moment. Cu in 
the planes forms a (well studied) spin-1/2 2D Heisenberg square lattice 
AF (nearest neighbors antiparallel) at low oxygen concentration (the 
Y123O6 end of the phase diagram), and the famous high-temperature 
superconductor when the oxygen sites between chain-Cu are filled, doping 
the electron holes into the planes.


If the system orders AF the planes ALWAYS form a square lattice spin-1/2 
AF with nearest neighbors antiparallel. So you need to assign numbers 
like Cu1 (for up) and Cu2 (for down) for Cu in the planes. The chain Cu 
is on a different crystalografic site and doesn't need numbering.


What I did not remember correctly is that since you have two plane site 
Cu even in the primitive cell you can, in fact, get away with a 1*1*1 
cell. BUT look in XCRYSDEN or something like it to make sure that your 
numbering makes nearest neighbors in the planes antiparallel! A 
configuration with parallel spins along the a- or b-axis should have 
significantly higher E_tot.


If you consider not only Y123O6 but introduce oxygen between Cu 
chain-sits you loose the 4-fold symmetry of the c-axis even in the 
non-magnetic case. This is why, as far as I recall, at least a 2*2*1 
supercell is necessary. To describe the different stacking sequences 
along the c-axis you will have to at least double the cell along the 
c-axis as well. See the above mentioned Phys Revs and the literature 
cited therein for the variety of AF phases that come about by different 
stacking of these planes along the c-axis depending on the oxygen 
content, or on the rare earth element.


As an additional comment: To my knowledge all evidence indicates that 
there is NO coexistence of AF-order and superconductivity. At 
intermediate oxygen content a phase separation occures into 
superconducting and AF phases.


Good luck with your calculations,

Martin Pieper

---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 16.05.2015 21:15, schrieb delamora:

This is a problem I had studied before, but non magnetic, so I was
curious to try the magnetic case; w
With YBa2Cu3O7 you have magnetism and superconductivty! braking one of
Matthias rules

The result I got for, YBa2Cu3O6, was that Cu1 MM=0.0007 or "non
magnetic" as far as the calculations show.
Cu2=0.5873 with U=4eV
So, you have to study only Cu2 for magnetism.
From my point of view you the most and I would guess only ordering of
the inplane spins is like a chess board, alternating un and dn.
the interplanar Cu2-Cu2 ordering can be up-up or up-dn, but since
there are no oxygen atoms between the planes the difference should be
quite small.

I did the calculation with RxK=7 and 100 k-points with 4 parallel
cores, it took half an hour.

In the supercell output you have to delete all the numbers
Ba 1 => Ba, O 1 => O and only number 1 and 2 the Cu as you want to 
order them

I did;
Cu 00x and 1/2,1/2,x as Cu 1 and later as 'up'
and for 0,1/2,x and 1/2,0,x as Cu 2 and later as 'dn'
Now you can have 00,-x as 'dn' and 0,1/2,-x as up and this gives
another ordering

De: wien-boun...@zeus.theochem.tuwien.ac.at
 en nombre de Madesis
Ioannis(John) 
Enviado: sábado, 16 de mayo de 2015 01:09 p. m.
Para: Wien
Asunto: Re: [Wien] AFM calculations for YBCO6

Mr. Delamora, first of all thank you for your dedication, and thorough
examination of my problem.

I haven't fully tested your solution, however, there are plenty of AFM
orderings that I wish to test such as A, G and C type, all of which are
different combinations of 

Re: [Wien] AFM calculations for YBCO6

[Madesis Ioannis(John)]

Hello Dr.Pieper and thank you for your contribution.

I hadn't seen your reply in my previous one.

What I did, and it seems to work for now, is the following:
-I began a new struct file out of nothing, with space group =1
-I then began placing all equivalent atoms for a 2x2x1 supercell, but 
everything by hand. At that step, I defined 3 different Cu atoms, as 
discussed, with all proper properties. Nearest neighbor at all 
directions, is opposite, etc.
-I then began the initialization steps of Wien2k, and it came up with a 
remarkable sqrt(2)xsqrt(2)x1 unit cell, as described in recent papers 
(First-principles calculation of electronic and structural properties of 
YBa 2 Cu 3 O 6+y Georgia Lopez et al 2010)


--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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