inizialization and databases

[Daniele Varsano]

Dear Sam,
the answer is: it depends.

It depends what do you want to calculate with this wavefunctions.
I think you can safely calculates optical properties in RPA or BSE.
Anyway there are problem for GW calculations. When calculating the
self-energy, you want to subtract the Vxc part of the ground state calculations:

<n|Sigma_x - Vxc|n> and Yambo it is not able to perform this operation:
<n|Vxc|n>.

May it is possible to ask pwscf to write this part and then ask yambo to read it
and subtract, but a little bit of coding is needed.

Cheers,

Daniele

PS: Non local exchange-correlation potential are implemented in Yambo, but unfortunately they are not
in the GPL version. Still check is needed. May be people working on that can add more information.

[samazadi]

Dear Andrea

I am using yambo 3.2.3 rev.676

I didn't get any problem. I used hybrid functional to do -g n -p p calculations to find QP band-gap.
the final QP band-gap comes from PBE0 input is much more larger (about 3.5 eV) than GGA orbitals.

Cheers
Sam

[Daniele Varsano]

Dear Sam,
Careful!!! this is the calculation you can't do starting from wavefunctions calcualated by hybrid functionals,
for the reason I explained you above.

Cheers,

Daniele

[samazadi]

Dear Daniele

Thanks for your explanation. So, I got wrong results !
I have to say I waste 4 days to get this wrong results
But, as Andrea said, it might be better that Yambo stops in such case.
By the way, this problem doesn't detract from Yambo value.
Thank you again for your answer.

Cheers
Sam

[samazadi]

Dear Daniele

Some of my Yambo calculations take long time, about 6-7 days.
But the max run time of the cluster I am using, is 5 days.
Is there any checkpoint restart facility in Yambo ?
I appreciate any idea to solve this problem.

Cheers
Sam

[Daniele Varsano]

Dear Sam,
yes there are some possibility to restart calculations,
what kind of calculations are you doing?
You can restart surely the excitonic matrix (Bethe Salpeter) construction, and calculation
of the screening (plasmon-pole) for the GW.

Cheers,

Daniele

[samazadi]

Dear Daniele

Thank you for reply. I am doing GW calculations with plasmon-pole approximation (-g n -p p)
Would you please tell me how can I restart GW calculations ?
Thanks in advance.

Cheers
Sam

[Daniele Varsano]

Dear Sam,
I'm not totally sure, but running the same input on the interrupted calculation,
Yambo should recognize it and continue it from where it was interrupted.

Cheers,

Daniele