[QE-users] Different ELF values with QE 7.0

[Roman Lucrezi]

Alright, thank you so much for your efforts and your support!
At least, it's good to know what's the source of the difference, and 
which QE version uses which ELF definition.

Roman

On 15.03.22 17:55, Paolo Giannozzi wrote:
> Now I remember: I left the new version of "fac" because it seemed more 
> coherent with the definition of the ELF; which means that all ELF 
> calculations before 6.8 might have been wrong, although by a 
> relatively small factor
>
> Paolo
>
> On Tue, Mar 15, 2022 at 4:49 PM Paolo Giannozzi 
> <p.giannozzi at gmail.com> wrote:
>
>     The third and fourth commits of this list:
>     https://gitlab.com/QEF/q-e/-/commits/develop/PP/src/elf.f90
>     extended ELF to spin-polarized cases. The factor "fac" was changed
>     from
>         fac = 5.d0 / (3.d0 * (3.d0 * pi**2) ** (2.d0 / 3.d0) )
>     to
>         fac = 5.d0 / (3.d0 * (6.d0 * pi**2) ** (2.d0 / 3.d0) )
>     These commits however introduced a bug (an out-of-bound error) in
>     the spin-unpolarized case that I fixed in the latest commit (first
>     of the list). I did not change the factor "fac", though. If you
>     revert to the previous value of "fac", you get the same numbers as
>     before for the spin-unpolarized case, or at least, this is what I
>     observed for a single case.
>
>     Having already wasted too much time on something I have no
>     interest in, I am waiting for instructions from ELF-friendly
>     people about the correct value of such a factor.
>
>     Paolo
>
>     On Tue, Mar 15, 2022 at 1:53 PM Roman Lucrezi via users
>     <users at lists.quantum-espresso.org> wrote:
>
>         Hey,
>
>         has anybody else experienced this behaviour in the ELF
>         calculation with QE v.7.0?
>
>         Kind regards,
>
>         Roman Lucrezi
>         Institute of Theoretical and Computational Physics
>         Graz University of Technology, Austria
>
>         --------------------------------------------------------------------------
>         Roman Lucrezi via users Tue, 08 Mar 2022:
>
>         Hi everybody,
>
>         recently I used QE v.7.0 to recalculate the 3D electron
>         localization function (ELF) in a system I had already worked
>         on with QE v.6.5, and obtained quantitatively quite different
>         results: e.g. for specific 2D cuts I get differences in the
>         range of 0 to 0.25 (for ELF(v.7.0)-ELF(v.6.5)), where the
>         v.7.0 results are always higher. I have rerun everything with
>         the exact same input files, trying v.6.5, v.6.7MaX and v.7.0:
>         v.6.5 and v.6.7MaX give the same results, v.7.0. is different
>         as described above. For each version I ran a non-polarized
>         (nspin = 1) scf calculation with scalar-relativistic PBE ONCV
>         pseudos, the system is metallic and I used a mp smearing.
>         After that, I used pp.x for the ELF and an XSF file with this
>         input (and varying prefixes):
>
>         &inputPP
>             prefix   = 'v6_5',
>             outdir   = './tmp'
>             plot_num = 8
>             filplot  = 'v6_5.elf.dat'
>         /
>         &plot
>             iflag         = 3,
>             output_format = 5
>             fileout       = 'v6_5.elf.xsf'
>         /
>
>         Do you have any idea on what could cause this discrepancy? I
>         saw in the release notes that there were some problems with
>         ELFs in the spin-polarized case, and there is also a line for
>         v.7.0, saying that the spin-UNpolarized ELFs were grossly
>         wrong in v.6.8. Does this affect only v.6.8, or each version
>         up to v.6.8, meaning that only v.7.0 gives correct results?
>
>         Kind regards,
>
>         Roman Lucrezi
>         Institute of Theoretical and Computational Physics
>         Graz University of Technology, Austria
>
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>
>
>     -- 
>     Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
>     Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
>     Phone +39-0432-558216, fax +39-0432-558222
>
>
>
> -- 
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
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