Yambo Community Forum

Dear Yambo developers,
I am trying to calculate the optical properties of some 2D structures. Due to the need of getting some information in a specific direction, I want to run nscf.in in the nonequal mesh (e.g. 8 4 1). During initialization, r_setup encompasses such a qmesh, whereas, in the next step (yambo -o -k Hartree) yambo.in is restricted by $\Gamma$ point (% QpntsRXd 1 | 1 |). I found that such a problem arise from the low symmetry embedded in my crystal structure. Could you please guide me to overcome this problem?

Best,
Mohammad

Dear Mohammad,
please sign your post with your affiliation, this is a rule of the forum and you can do once for all filling the signature in the user profile.
The problem is due to the fact the yambo sees 2 equivalent points in the rlu q-grid
You can try to delete your ./SAVE/ndb* files and rerun the setup uncommenting the keyword NoDiagSC in the input file. (you can generate the file using yambo -i -V all)

Best,
Daniele

Dear Daniele,
Thanks for your reply. After applying your advice, the problem remains unsolved. That is, the following line is displayed in the r_setup:

"[RL indx] Q BZ pts are /= from X grid BS pts. Gamma point only."

Best,
Mohammad

Dear Mohammad,
can you post the r_setup and input files?

Before that can you try the following:
*delete all the ./SAVE/ndb.* files
*edit an input file containing only:

setup
NoDiagSC

*run the code

Best,

Daniele

Dear Daniele,
Solved. I am grateful for your help.

Best,
Mohammad

Great,

we have two algorithms to setup the q grid. The default one sometimes fails when dealing with non-orthorhombic cells e.g. hexagonal lattice, the second one is activated with the keyword NoDiagSC. Probably we should change the default in the future.

Best,

Daniele