Re: [Wien] Primitive Brillouin zone of Monoclinic base-centered structure

[Marcelo Barbosa]

Thank you very much for you suggestion!

I calculated the primitive reciprocal vectors by hand considering the same 
coordinate system as XCrySDen uses for the primitive cell and found out that in 
fact it gets the right reciprocal vectors for this space group. Only the 
primitive Brillouin zone that is drawn for the band path selection is wrong.
Therefore, by manually introducing the k-points coordinates of the desired 
points in the table that shows up for the band structure script, I was able to 
create the correct xcrysden.klist file to be used by WIEN2k.

Since the high-symmetry points were known for the C2/m representation of the 
space group, I just used the transformation matrix as described in “Part 5. 
Transformations in crystallography” of Volume A from the “International Tables 
for Crystallography” (as suggested in the email) to get the high symmetry 
points coordinates in the B2/m representation.

Once again, thank you very much for your help.

Best regards,
Marcelo


> On 5 Oct 2017, at 21:25, Gavin Abo  wrote:
> 
> I don't know if it helps or not:
> 
> I could be wrong, but I believe XCrySDen has a bug for the b-centered 
> monoclinic:
> 
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg06205.html 
> 
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12479.html 
> 
> 
> However, I haven't looked into it further.
> 
> The "International Tables for Crystallography" [ 
> http://dx.doi.org/10.1107/9780955360206001 
>  ] likely contains a 
> transformation (rotation matrix) that you could use, but I don't know what 
> volume or page it would be on.  Maybe it is in "Part 5. Transformations in 
> crystallography" of Volume A [ http://it.iucr.org/Ab/contents/ 
>  ].
> 
> On 10/5/2017 5:01 AM, Marcelo Barbosa wrote:
>> Dear Sirs,
>> 
>> I tried the following solution to my problem but it seems that changing the 
>> space group to P1 makes the Primitive Brillouin Zone to be equal to the 
>> Conventional Brillouin zone.
>> However, for a base-centered monoclinic structure, they are not equal and to 
>> get the right band structure one must use the Primitive Brillouin zone high 
>> symmetry points (as have been shown in 
>> https://doi.org/10.1016/j.commatsci.2010.05.010 
>> ).
>> 
>> In that article, they have a table with all the symmetry points for a 
>> base-centered monoclinic structure.
>> Unfortunately, they consider the lattice vectors with alpha < 90º instead of 
>> the gamma != 90º required by WIEN2k.
>> How can I transform those points from one representation to another?
>> And if I can calculate those points, can I manually choose them in XCrysden 
>> to generate the klist file instead of choosing them from the 3D image (since 
>> the image is wrong)?
>> 
>> Best regards,
>> Marcelo
>> 
>>> On 22 Sep 2017, at 19:09, Yundi Quan >> > wrote:
>>> 
>>> It happens sometimes. One possible workaround is to set the space group to 
>>> P1 and use the same a, b, c, alpha, beta and gamma. That way you can select 
>>> k-points and use the for C2/m structure.
>>> 
>>> On Fri, Sep 22, 2017 at 4:00 AM, Marcelo Barbosa 
>>> mailto:marcelo.b.barb...@gmail.com>> wrote:
>>> Dear Sirs,
>>> 
>>> I’m trying to get the Brillouin zone and high-symmetry points of Ga2O3, 
>>> which has a monoclinic base-centered lattice.
>>> However, after plotting it using XCrysDen, one of the vectors (b*) doesn’t 
>>> go through the center of any plane in the Brillouin zone (see figure in 
>>> attachment).
>>> Since the Brillouin zone is defined has the Wigner-Seitz cell of the 
>>> reciprocal lattice, shouldn’t all the reciprocal vectors go through the 
>>> center of the planes by definition?
>>> 
>>> To generate the structure, I used the following .cif file (CIF 
>>> ) but since the parameters 
>>> in the file are in the C 2/m representation, I started by running "x 
>>> sgroup” to get the structure with the parameters in the B 2/m 
>>> representation (as WIEN2k requires).
>>> 
>>> Thank you for your help.
>>> 
>>> Best regards,
>>> Marcelo
>>> 
>>> 
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Re: [Wien] Optimization of monoclinic structure

[Gavin Abo]

I don't remember.  Probably all parameters are fixed except for one of 
them, then this is repeated separately for each parameter:


A, B, C fixed with changing GAMMA value, then
A, B, GAMMA fixed with changing C value, then
...
B, C, GAMMA fixed with changing A value

"x optimize" or OrthoOpt probably automatically set up the set of 
calculations in this way in a job script like optimize.job and then the 
job script is used to run all the calculations [ 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16418.html 
].


From the sounds of it, you are setting up each calculation by hand 
instead of using one of the above scripts/programs to help with that.


For monoclinic optimization, make sure the monoclinic angle (i.e., the 
one angle that is not equal to 90) is set as gamma.  As maybe this could 
cause the "SELECT" error due a symmetry break [ 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12124.html 
].


The "SELECT" error could also be caused by other things.  See the "NO 
ENERGY LIMITS FOUND IN SELECT" on page 231 under section "12 Trouble 
shooting" in the WIEN2k 17.1 usersguide [ 
http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf ], 
where is says:


"Usually this happens when your input is not ok, or for very ill 
conditioned problems (very rare), or more likely, when “Ghostbands” 
appeared (or some states were missing) because of bad energy parameters 
in case.in1."


input is not ok => In an optimization, you are distorting the structure 
(changing the lattice parameters).  It is probably straightforward that 
if you distort a structure too much (% change is too large)  while you 
are doing this, you could possible generate a bad case.struct file.


As the above sentence also says, it could be caused by ghost bands. To 
help with that, there is section "12.1 Ghost bands" starting on page 232 
in the WIEN2k usersguide.


A related error might be the QTL-B error.  Refer to the links found in 
the post at:


https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12625.html

On 10/15/2017 8:26 PM, Shalika R. Bhandari wrote:

Dear all, Thank you for your suggestions .
 Now I have a bit confusion like while optimizing monoclinic structure 
does A, B,C,and GAMMA changes at the same time or we need to do them 
separately?
Also while running optimization, after first cycle it shows ERROR and 
stops running. LIKE THIS..

46.9u 0.0s 0:47.75 98.4% 0+0k 3696+40656io 12pf+0w
1.3u 0.0s 0:01.59 89.3% 0+0k 73552+35336io 6pf+0w
clmextrapol_lapw has generated a new RELAX.clmdn
hup: Command not found.
changing RELAX.in2c
changing RELAX.in2_ls
changing RELAX.in2_st
changing RELAX.in2_sy
 LAPW0 END
SELECT - Error

>   stop error
ERROR status in RELAX_mon1.00

I Want some more suggestions to resolve this problem sir.

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[Wien] Optimization of monoclinic structure

[Shalika R. Bhandari]

Dear all, Thank you for your suggestions .
 Now I have a bit confusion like while optimizing monoclinic structure does
A, B,C,and GAMMA changes at the same time or we need to do them separately?
Also while running optimization, after first cycle it shows ERROR and stops
running. LIKE THIS..
46.9u 0.0s 0:47.75 98.4% 0+0k 3696+40656io 12pf+0w
1.3u 0.0s 0:01.59 89.3% 0+0k 73552+35336io 6pf+0w
clmextrapol_lapw has generated a new RELAX.clmdn
hup: Command not found.
changing RELAX.in2c
changing RELAX.in2_ls
changing RELAX.in2_st
changing RELAX.in2_sy
 LAPW0 END
SELECT - Error

>   stop error
ERROR status in RELAX_mon1.00

I Want some more suggestions to resolve this problem sir.
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