[QE-users] k-point algorithm is not tested yet turbo davidson

Wed Dec 18 21:36:51 CET 2019

Forgot to mention, it only happens if I do not assign any charge to the
structure i.e., for neutral case. However, it works for nonzero tot_charge,
spin-unpolarized situation with fixed smearing and turb_davidson works fine.

Thanks for your comments.

Best,
Abhirup
-------------------------------------------------------------------------------------------------------------------------------------
Abhirup Patra
Postdoctoral Research Fellow
Department of Chemistry
University of Pennsylvania

On Wed, Dec 18, 2019 at 3:29 PM Abhirup Patra <abhirupp at sas.upenn.edu>
wrote:

> Thanks, Iurii. Yes, the spectrum with gamma point is quite reasonable but
> do not match with the experimental observation. It could be some other
> issue.
>
> However, I am wondering how to do the TDDFT calculation for a
> doped/defected structure with extra electron or hole. I tried to use
> turbo_davidson starting from i) scf calculation with npsin= 2 and total
> magnetization and turbo_davidson does not work since I believe it does not
> for spin-polarized system, then, I tried ii) scf calculation without any
> spin-polarization and the scf calculation did not run since it cannot work
> with an extra charge and 'fixed' occupation, and, finally, iii) scf with
> smearing but turbo_davidson does not support scf calculation with smearing
> (ref:
> https://lists.quantum-espresso.org/pipermail/users/2017-January/037363.html)
>
>
> I believe in this case I cannot use TDDFT of QE to calculate absorption
> spectra of a defected or doped structure. Am I right here?
>
> Best,
> Abhirup
>
>
>
> -------------------------------------------------------------------------------------------------------------------------------------
> Abhirup Patra
> Postdoctoral Research Fellow
> Department of Chemistry
> University of Pennsylvania
>
>
> On Wed, Dec 18, 2019 at 4:00 AM Timrov Iurii <iurii.timrov at epfl.ch> wrote:
>
>> Dear Abhirup,
>>
>>
>> > However, I am not sure with the number of atoms (~120 or more) GW-BSE
>> calculations with supercell is actually feasible.
>>
>>
>> Yes, I understand the issue. I do not know if it is feasible. You may try
>> to use e.g. Yambo and see how it goes. Otherwise, since you have already
>> quite a big cell, maybe with k=0 you obtain quite a reasonably converged
>> spectrum (to be checked w.r.t. the cell size)  at the TDDFT level in the
>> adiabatic approximation.
>>
>>
>> Regards,
>>
>> Iurii
>>
>>
>> --
>> Dr. Iurii Timrov
>> Postdoctoral Researcher
>> STI - IMX - THEOS and NCCR - MARVEL
>> Swiss Federal Institute of Technology Lausanne (EPFL)
>> CH-1015 Lausanne, Switzerland
>> +41 21 69 34 881
>> http://people.epfl.ch/265334
>> ------------------------------
>> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of
>> Abhirup Patra <abhirupp at sas.upenn.edu>
>> *Sent:* Tuesday, December 17, 2019 4:47:01 PM
>> *To:* Quantum ESPRESSO users Forum
>> *Subject:* Re: [QE-users] k-point algorithm is not tested yet turbo
>> davidson
>>
>> Thanks very much, Iurii. I really appreciate your answer and it does make
>> sense to me. With gamma point only it works fine. And, you are  right, my
>> system is a solid and I am
>> trying to simulate the optical spectrum. However, I am not sure with the
>> number of atoms (~120 or more) GW-BSE calculations with supercell is
>> actually feasible.
>>
>> Best,
>> Abhirup
>>
>> -------------------------------------------------------------------------------------------------------------------------------------
>> Abhirup Patra
>> Postdoctoral Research Fellow
>> Department of Chemistry
>> University of Pennsylvania
>>
>>
>> On Tue, Dec 17, 2019 at 7:50 AM Timrov Iurii <iurii.timrov at epfl.ch>
>> wrote:
>>
>>> Dear Abhirup,
>>>
>>>
>>> As you can see from the error message of the turbo_davidson code, the
>>> k-points algorithm is not supported. Only Gamma point sampling can be used.
>>>
>>>
>>> If I understand correctly, your system is a solid, right? And you want
>>> to use a unit cell with a k-points mesh, right? The turbo_davidson cannot
>>> be used in this case. You may try to use a supercell with a Gamma point
>>> sampling. But be careful when using TDDFT in the adiabatic approximation
>>> for the absorption spectroscopy of solids. I recommend that you check
>>> literature on this topic. Maybe you will need to resort to the BSE approach.
>>>
>>>
>>> HTH
>>>
>>>
>>> Iurii Timrov
>>>
>>>
>>> --
>>> Dr. Iurii Timrov
>>> Postdoctoral Researcher
>>> STI - IMX - THEOS and NCCR - MARVEL
>>> Swiss Federal Institute of Technology Lausanne (EPFL)
>>> CH-1015 Lausanne, Switzerland
>>> +41 21 69 34 881
>>> http://people.epfl.ch/265334
>>> ------------------------------
>>> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of
>>> Abhirup Patra <abhirupp at sas.upenn.edu>
>>> *Sent:* Monday, December 16, 2019 6:12:08 PM
>>> *To:* Quantum ESPRESSO users Forum
>>> *Subject:* [QE-users] k-point algorithm is not tested yet turbo davidson
>>>
>>> Hello,
>>>
>>> I am trying to use turbo_davidson starting from a SCF calculation using
>>> PBE without smearing and spin-polarization. This system is a non-metal with
>>> bandgap of 2.6 eV. I gave uniform k-mesh as follows for the bcc structure
>>> with lattice constant of 10.34 angstrom.
>>>
>>>  K_POINTS {crystal_b}
>>>  9
>>> 0.0 0.0 0.0 0
>>> 0.0 -0.5 0.0 0
>>> 0.0 -0.5 0.5 0
>>> 0.5 -0.5 0.5 0
>>> 0.5 -0.5 0.0 0
>>> 0.5 0.0 0.0 0
>>> 0.0 0.0 0.0 0
>>> 0.0 0.0 0.5 0
>>> 0.5 0.0 0.5 0
>>>
>>> &lr_input
>>>     prefix = 'pristine_pbe'
>>>     outdir = './'
>>> !    wfcdir = './'
>>> /
>>> &lr_dav
>>>   num_eign = 35,
>>>   num_init = 70,
>>>   num_basis_max = 200,
>>>   start = 0.0d0
>>>   finish = 3.5d0
>>>   step = 0.001d0
>>>   broadening = 0.005d0
>>> /
>>>
>>> However, I am getting the following error:
>>>
>>>      Error in routine lr_readin (1):
>>>      k-point algorithm is not tested yet
>>>
>>> I am wondering if there is a simple way out to this problem other than
>>> explicitly testing different k mesh combinations.
>>>
>>> Best,
>>> Abhirup
>>>
>>> -------------------------------------------------------------------------------------------------------------------------------------
>>> Abhirup Patra
>>> Postdoctoral Research Fellow
>>> Department of Chemistry
>>> University of Pennsylvania
>>> _______________________________________________
>>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso
>>> )
>>> users mailing list users at lists.quantum-espresso.org
>>> https://lists.quantum-espresso.org/mailman/listinfo/users
>>
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