Dear Giuseppe,
I think that I could answer to the first question.
In linear response the exx integral are different respect with to ground
state calculation, because they contain the response wavefunction, so
you need three different ACE operators (without response wfc, with
response wfc, with conjugate response wfc); I’m not sure that it is
convenient. Second problem, we have to think back an another algorithm
to introduce the self-consisted cycle for ACE operator.
But if you have some suggestions, we can call each other.
Best regards,
Oscar Baseggio
Il 2020-04-15 23:59 Giuseppe Mattioli ha scritto:
Dear Iurii
The "TDDFT-solid state affair" seems to periodically resurface from
deep waters... Most of it started (at least for me) from a 2008 paper
by Izmaylov&Scuseria (J. Chem. Phys. 2008, 129, 034101) in which some
assumptions on the usage of range-separated functionals such as HSE
were made on the grounds of theory and of a (cumbersome...) example of
an H chain. There is now a vast literature on the tailoring of
appropriated range-separated hybrid functionals for solid-state TDDFT,
because we are stubborn and do not basically cope with the fact that
you can do (almost) whatever you want with TDDFT in the case of 0D
system, and that all these wonderful things are reduced to some sort
of poor "joint density of states" in the case of 3D systems! :-D
I would be very happy to read a comment from you: after years of
painful applications of EXX to QE calculations, which I've pioneered,
with ACE and ecutfock we have now found a very honorable balance
between speed and accuracy of ground state calculations (with NC PPs,
in my experience, but this is another matter). The quest for a
possible missing rung of the Jacob's excited-state ladder between
epsilon.x and GW-BSE might be at hand. Thus:
1) Do you think that further effort in the implementation of k_points
coupled with range-reparated (or even optimally-tuned-like) xc
functionals working with ACE and ecutfock in turbo_lanczos/davidson
might provide such a valuable tool?
2) Do you think that such kind of calculation might show (after a lot
of work, admittedly) a speedup, with respect to a GW-BSE calculation
of the same system, so spectacular that the juice is worth the
squeeze?
Thanks in advance to you and to everybody for any feedback
Giuseppe
Quoting Timrov Iurii <iurii.tim...@epfl.ch>:
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 <users-boun...@lists.quantum-espresso.org> on behalf of
Michal Krompiec <michal.kromp...@gmail.com>
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
<oleksandr.motor...@polytechnique.edu> 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 <users-boun...@lists.quantum-espresso.org> on behalf of
Michal Krompiec <michal.kromp...@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
_______________________________________________
Quantum ESPRESSO is supported by MaX
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_______________________________________________
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--
Oleksandr Motornyi
PhD candidate
Laboratoire de Solides Irradies
Ecole Polytechnique (Palaiseau, France)
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GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
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E-mail: <giuseppe.matti...@ism.cnr.it>
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