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

Wed Dec 18 21:29:48 CET 2019

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
>> _______________________________________________
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