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

[Abhirup Patra]

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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