On 5/26/24 23:20, Abdesalem Houari via users wrote:
After checking well the exchange-correlation document
(Modules/funct.f90), my first issue seems resolved.
and the second as well: absolute energies depend upon the pseudopotentials
Paolo
I found that "pbe" = "sla+pw+pbx+pbc" (=
XC-001I-004I-003I-004I-000I-000I).
So the true PBE needs, not only "pbx" exchange + "pbc" correlation, but
also "sla" exchange + "pw" correlation.
Thanks.
A. Houari
On Sunday, 26 May 2024 at 08:54:24 pm GMT+1, Abdesalem Houari via users
<[email protected]> wrote:
Dear All,
I wanted to do a calculation test using PBE-functional from LIBXC and
compare it to the internal QE one. As a test, I opted for body centered
cubic (bcc) iron.
I'm a bit puzzled by the differences in the results.
- First, for PBE from LIBXC, following the QE user-guide on how to use
LIBXC, I put the following input:
*input_dft='XC-000I-000I-101L-130L-000I-000I*'. I obtained a total
energy value of -39.08694619 Ry.
- Then, for QE internal PBE functional, after having a look to
Modules/funct.f90 file, I deduced the PBE should be forced from the
input as follow:**input_dft='XC-000I-000I-003I-004I-000I-000I*'.* Here I
was quite surprised obtaining a different value of the total energy
-31.22123378 Ry... It seems like it is not the correct PBE ?
- When I just use NC-PP (Fe.pbe-mt_fhi.UPF) without forcing the
input_dft, I get a similar result to LIBXC-PBE ... The same result is
obtained also when I forced the input_dft, but including LDA-exchange
(Slater)+correlation (PW) i.e.
**input_dft='XC-001I-004I-003I-004I-000I-000I*'*
*
*
I'm really confused ! I**would be grateful if some could give a bit of
explanation, on how the input_dft works exactly ? especially with
respect to the Module/funct.f90 file which gives all the internal
functionals.
I would also ask for another issue. It is explained in the PW manuel
that input_dft overrides the PP. Normally, if I'm not wrong, whatever
the kind of the PP given in the input file (PBE or other;
norm-conserving or ultra-soft or PAW potential), the code will discard
it and does not look at it at all when input_dft is forced.
Here also I'm confused, I forced the input_dft as:
**input_dft='XC-001I-004I-003I-004I-000I-000I*'*, with two different PP
(Fe.pbe-mt_fhi.UPF and Fe.pbe-spn-rrkjus_psl.0.2.1.UPF); and the total
energies are completely different ! *
*
*
*
Thanks a lot in advance*
*
Sincerely yours.
========================================
Dr. Abdesalem HOUARI
-------------------------------------------------------------------------------------------
Department of physics, Theoretical Physics Laboratory
University of Bejaia-06000. Algeria.
E-mail: [email protected] & [email protected]
https://sites.google.com/site/houariabdeslam/homepage
<https://sites.google.com/site/houariabdeslam/homepage>
========================================
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
<mailto:[email protected]>
https://lists.quantum-espresso.org/mailman/listinfo/users
<https://lists.quantum-espresso.org/mailman/listinfo/users>
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine Italy, +39-0432-558216
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
