[QE-users] Different ELF values with QE 7.0

[Paolo Giannozzi]

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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