Yambo Community Forum

Dear Yang,

I have tried to lower the kinetic energy cut-off in scf calculation. But the total G vector number doesn't vary with the kinetic energy cut-off.

This is a bit strange, it should change by definition. The number of G-vectors is determined by the ecutrho input variable. If you do not have defined, it is set to 4 times the cutoff for the wavenfution (ecutwfc), assuming you are using norm-conserving pseudopotential. In case you are using ultrasoft pseudos, this is an experimental feature in Yambo and it is strongly discouraged.

If you want you can post your nscf input file of QE and we will have look. Actually, I do not know where the problem in reading the ns.db1 database comes from, maybe someone more expert than me in netcdf library can help you on this issue. In any case a calculation with 20M G-vector I would say that it is unfeasable.
Best,
Daniele

Dear Yang,

the ratio of charge density and wfc plane waves (defined by ecutrho and ecutwfc, respectively) is far from ~8, which should be
the expected value when ecutrho=4*ecutwfc (as is mathematically defined for norm-conserving pseudopot).
The numbers you obtain are quite suspicious.
Are you setting ecutrho independently ?
Can you post your scf/nscf input ? (without this I think we won't be able to help much further).

take care
Andrea

Can you post the output of
Best,
D.

Dear Andrea and Daniele,

Yes, you are right. I set ecutrho independently and didn't reset it when I changed kinetic energy cut-off before. That is why the G-vector keep unchanging. The problem is solved now. The number of G vector decreases to 4885279 after I change ecutrho. And Yambo can work now. Thank you very much. It is really helpful.

Best,
Yang

Dear Team Yambo,

I'm facing the following issue when I'm trying to generate the SAVE file using p2y command.
The error comes out as .

Help needed.

Thanks,
Pushpendra

Dear Pushpendra,

do you have the right permission to write files in the directory you are running?
If you can write files, then please provide more details (yambo release / log file before the error etc / any other info can help to post the problem).

Best,

Daniele

Dear Daniele,

Yes, I have permission to write files in the same directory ( for example the quantum espresso calculation is running smoothly in the same directory).
I'm using the Yambo 5.0.0 (yambo master).

Also, when I'm running yambo with the already created 'SAVE' database it is showing the following error- Thanks,
Pushpendra

Dear Pushendra,
it seems there are some problems with compilation/lining of the netcdf libraries.
Can you post your config.log file?

Best,

Daniele

Dear Daniele,

Sorry for the late reply.
We have checked that there are no permission problems in the concerned folder.
Apparently, it is encountering some "undefined variable" during the p2y writing phase.

I'm attaching here the config.log file of the installation.
Thank you,
Pushpendra