[QE-users] safe to enable "k-point algorithm" in turbo_lanczos?

[Oleksandr Motornyi]

Dear Michal,


The k-points algorithm of turbo_lanczos.x as it is does not give the 
correct results if there is more than one single k-point. However you 
can look up the Lanczos implementation in the thermo_pw module, which 
works fine with k-points as far as I remember (of course bare in mind 
what Iurii said about Adiabatic TDDFT).


Regards,

Oleksandr

On 15/04/2020 19:35, Timrov Iurii wrote:
>
> Dear Michal,
>
>
> The k-points implementation of turbo_lanczos.x was not tested and 
> hence it is disabled. But most importantly, very likely there are bugs 
> (I think I know a few). Someone has to work on it and fix bugs. But is 
> there a motivation to do so? Adiabatic TDDFT with LDA/GGA is known to 
> be not accurate for the optical absorption spectroscopy of solids.
>
>
> Greetings,
>
> Iurii
>
>
> --
> Dr. Iurii Timrov
> Postdoctoral Researcher
> STI - IMX - THEOSand 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 
> Michal Krompiec <michal.krompiec at gmail.com>
> *Sent:* Wednesday, April 15, 2020 7:26:09 PM
> *To:* Quantum Espresso users Forum
> *Subject:* [QE-users] safe to enable "k-point algorithm" in 
> turbo_lanczos?
> Hello,
> I'm trying to compute the spectrum of a crystalline insulator using
> turbo_lanczos. I got the following error:
>
>      Error in routine lr_readin (1):
>      k-point algorithm is not tested yet
>
>
>
> I guess I could just comment line 477 out in TDDFPT/src/lr_readin.f90
> to disable this error:
>
>        ! K-points are implemented but still unsupported (use at your 
> own risk!)
>        !
>        IF (.NOT. gamma_only ) CALL errore('lr_readin', 'k-point
> algorithm is not tested yet',1)
>
> But how unstable is this code? Any reason not to try this?
>
> Thanks,
>
> Michal Krompiec
> Merck KGaA
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-- 
Oleksandr Motornyi
PhD candidate

Laboratoire de Solides Irradies
Ecole Polytechnique (Palaiseau, France)

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