Dear Michal,
> @Iurii: the motivation (or rather - hope) is that TDDFT (or > perhaps even epsilon.x) will give us the correct trend, whilst being > much cheaper than GW/BSE (which we are trying as well). You can try to use the turboEELS code with a very small transferred momentum q. The code prints at the end the loss function -Im[1/eps(w,q)] but also Im[eps(w,q)]. In the long wavelength limit Im[eps(w,q->0)] gives you the optical absorption spectrum at the TDDFT level in the adiabatic approximation with a LDA/GGA functional (see e.g. Fig. 3 in Comput. Phys. Commun. 196, 460 (2015)). 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 <[email protected]> on behalf of Michal Krompiec <[email protected]> Sent: Wednesday, April 15, 2020 7:54:32 PM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] safe to enable "k-point algorithm" in turbo_lanczos? Dear Oleksandr, Dear Iurii, Thank you very much, I understand that this code should rather stay disabled. @Iurii: the motivation (or rather - hope) is that TDDFT (or perhaps even epsilon.x) will give us the correct trend, whilst being much cheaper than GW/BSE (which we are trying as well). Best, Michal On Wed, 15 Apr 2020 at 18:39, Oleksandr Motornyi <[email protected]> wrote: > > 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 - 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 <[email protected]> on behalf of Michal > Krompiec <[email protected]> > 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 > _______________________________________________ > Quantum ESPRESSO is supported by MaX > (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > _______________________________________________ > Quantum ESPRESSO is supported by MaX > (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > -- > Oleksandr Motornyi > PhD candidate > > Laboratoire de Solides Irradies > Ecole Polytechnique (Palaiseau, France) > > _______________________________________________ > Quantum ESPRESSO is supported by MaX > (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
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