HSE@BSE with Yambo

[lamia]

Dear developers,

I would like to perform BSE calculations on top of HSE.
I performed all necessary calculations with Quantum Espresso 6.0. However, at the p2y conversion stage, I already received this warning:


-------
<---> [01] CPU structure, Files & I/O Directories
<---> [02] CORE Variables Setup
<---> [02.01] Unit cells
<---> [02.02] Symmetries
<---> [02.03] RL shells
<---> [02.04] K-grid lattice
<---> [02.05] Energies [ev] & Occupations
<---> [03] Transferred momenta grid
<---> [WARNING][RL indx] 2 equivalent points in the rlu grid found
<---> [RL indx] X grid is not uniform. Gamma point only.
<---> [03.01] External/Internal QP corrections
<---> [04] Response Functions in Transition spaceSegmentation fault (core dumped)

--------
So, I would like to know if there is a way to do BSE on top of HSE?

Best,
Lamia

[Daniele Varsano]

Dear Lamia,

the problem you are facing most probably is not related to the HSE functional.
Anyway, at the moment calculation on top of HSE are problematic for the GW calculations (inconsistency in the evaluation of the <Vxc> terms due to a different treatment of the divergencies). While if you are interested in BSE only without the GW step (e.g. opening the gap with scissor operator) it should be possible.

The problem you have here is due to the fact Yambo does not recognize the K point grid as uniform:

> [RL indx] X grid is not uniform. Gamma point only.

If you post your QE input file we can have a look and try to spot the problem.

Best,
Daniele

[lamia]

Dear Daniele,

Thanks for your kind reply.
Actually, yes I am interested in BSE only without the GW step.
Please check input in the attachment.

Best,
Lamia

[Daniele Varsano]

Dear Taouil,
it seems that yambo has a problem in dealing with your cell. It is a problem we have already faced and solved in the developing version of the code.
We will update the GPL source very soon in order to solve this problem. In the meanwhile, you can try to repeat your calculation by setting ibrav=0 and defining your cell by using the CELL_PARAMETERS keyword. Most probably this would not solve your problem but you can give a try.

Please note also that you are not adding empty states in your input file, so the BSE matrix cannot be calculated.
Other suggestion is to update your qe source: I see that you are using qe6.0 and many improvements have been done in the calculation with hybrid functionals since then.

Best,
Daniele