Yambo Community Forum

Dear Daniele

Many thanks for this. Returning to the original topic of this thread (and hopefully my last question!) I have used the non-diagonal yambo initialisation algorithm on another large cell. I'm not convinced by the r_setup output as in the 'transferred momenta grid' it states that the X-grid isn't uniform (while the previous time it was uniform when I used this algorithm). Is it OK to proceed with yambo calculations on this unit cell? See the attached r_setup file for more details.

Best wishes,

Alan

Dear Alan,
the grid is not seen as uniform, so you will not be able to perform other calculation as it is a pre-requisite.
Best,
Daniele

Dear Daniele

Do you have any suggestions how to make the grid uniform? The unit cell I am using is:

CELL_PARAMETERS angstrom
8.5251951 0.0000000 0.0000000
8.4900779 18.1877318 0.0000000
-7.8293296 -0.9350283 34.1550336

and the kpoint grid is that given by:

K_POINTS automatic
6 2 1 0 0 0

I can try a few other k-point grids arbitrarily, but I'm unsure for the problem with this one?

All the best,

Alan

Dear Alan,
no, I do not have suggestions. It just looks me strange you have these cells for a 2D system, as for a 2D system you should be able to choose the non-periodic direction orthogonal to the plane when the system lies. This would help a lot.
Best,
Daniele

Dear Daniele

Many thanks for the advice. I found that by rotating my system I was able to get the initialisation to interpret the X grid as uniform. However, in the 'Transferred momenta grid' I now receive the note:


System with reduced dimensionality
Smallest q vectors (crystal coordinates) :
0.250000 0.250000 0.000000

Is this something I need to be concerned about, or is it OK to proceed with yambo calculations from here? I attach the r_setup file.

Best wishes,

Alan

Dear Alan,
the r_setup is not attached, anyway, as long as you have a uniform grid you do not need to worry.
Best,

Daniele

Dear Daniele

Apologies, now attached (for completeness). The X grid is uniform so that's good to hear!

All the best,

Alan

Dear Daniele

Apologies, one more question on this. I managed to get a uniform X-grid for the initialisation. I then did a screening calculation and this ran fine. However, when I tried to do a BSE calculation yambo interpreted the X-grid as not uniform, even though it said this was uniform in the initialisation. I used NoDiagSC as an input for the BSE calculation so I'm a bit confused why this happened. In the previous (very similar) system this thread was originally about I didn't see this problem.

I attach relevant files (energy section removed so small enough file size for upload), let me know if you need any other details for me. Any suggestions would be much appreciated.

Best wishes,

Alan

Dear Alan,
I can't see NoDiagSC in the mirror of the input file reported in r-Bblk1_optics_bse_bss_rim_cut_01.txt.
Try to move it at the end of the input file, i.e. do not insert it among the runlevels.

Best,
Daniele

Dear Daniele

I tried this but nothing changed. I should note that in the previous system putting it in the run-levels still fixed the problem.

What else should I check?

With best wishes,

Alan