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

Thu Dec 19 17:40:47 CET 2019

Dear Iurii,

Thanks for the email. Sorry about not explaining it well. Here is what I
meant: With spin-polarization and with gamma only kmesh none of the TDDFT
code works (i.e. turbo_davidson, turbo_eels, turbo_lanczos). So it is
difficult to simulate optical spectra for a "neutral (tot_charge = 0)"
doped/defected structure. By "works", I meant that I could run the regular
scf-calculation and TDDFT codes for any "non-zero (tot_charge = -1 or +1)"
charged structure using "gamma only" kmesh and "non spin-polarization".

Please let me know if it's still confusing.

Best,
Abhirup

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

On Thu, Dec 19, 2019 at 4:06 AM Timrov Iurii <iurii.timrov at epfl.ch> wrote:

> Dear Abhirup,
>
>
> Sorry, I miss the point. Could you clarify please what do you mean by
> saying "it works"? Do you refer to the k-points implementation of the
> turbo_davidson code or something else? The k-points algorithm must be
> disabled for all cases (neutral and charged cases), and if this not the
> case, then I will modify the code in order to disable it.
>
>
> Best,
>
> 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:* Wednesday, December 18, 2019 9:36:51 PM
> *To:* Quantum ESPRESSO users Forum
> *Subject:* Re: [QE-users] k-point algorithm is not tested yet turbo
> davidson
>
> 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
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>>>
>>> _______________________________________________
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>>
>> _______________________________________________
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