[QE-users] Missing empty state in SCF calculation

[Stefano Baroni]

You may want to try to randomize the LUMO molecular orbital. SB

___
Stefano Baroni, Trieste -- http://stefano.baroni.me

> On 1 Sep 2023, at 19:51, Paolo Giannozzi <paolo.giannozzi at uniud.it> wrote:
> 
> On 01/09/2023 18:17, Lorenzo Sponza wrote:
> 
>> Dear Paolo, thanks for the answer.
>> I made a check running the same two calculations using the CG
>> diagonalization scheme instead of Davidson. The issue persists. May I
>> send you the input files ?
> 
> not a good idea, because I don't think it is a bug and don't have a solution at hand. You may open an issue on gitlab, though.
> 
> Paolo
> 
>> Best
>> Le 2023-09-01 16:49, Paolo Giannozzi a écrit :
>>> Iterative diagonalization may occasionally miss one or a few states if
>>> the starting manifold does not contain enough components of the
>>> missing states. As long as you do not miss any states in the occupied
>>> manifold, not a big deal for the ground-state calculation (but not for
>>> the band gap, of course)
>>> 
>>> Paolo
>>> 
>>> On 9/1/23 16:41, Lorenzo Sponza wrote:
>>>> 
>>>> You don't often get email from lorenzo.sponza at onera.fr. Learn why this
>>>> is important <https://aka.ms/LearnAboutSenderIdentification>
>>>> 
>>>> 
>>>> Dear all,
>>>> 
>>>> I encounter an issue I did not expect and I would like to know why it
>>>> happens and how I am suppose to handle it. I'm running an SCF
>>>> calculation of a gapped system (occupations = 'fixed'). If I include a
>>>> large number of empty bands, these are the energies in Gamma:
>>>> 
>>>> -4.8200-4.3169-0.9586-0.5478-0.5196-0.4977-0.0537 0.0095 with
>>>> occupations 1.0000 1.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
>>>> 
>>>> Instead, if I include only one empty band the result is
>>>> 
>>>> -4.8200-4.3169-0.5477 with occupations 1.0000 1.0000 0.0000
>>>> 
>>>> It's like in if the latter case I was missing the state at -0.9586 eV.
>>>> How it happens ?
>>>> 
>>>> I'm rising this issue because I'm checking the gapwidth of a series of
>>>> similar systems. I actually thought that it was safe to run simple SCF
>>>> calculations with 1 empty state, but I realise that results are
>>>> possibly wrong. Shall I mandatorily rely on NSCF calculations or I'm
>>>> making a mistake somewhere ?
>>>> 
>>>> Best regards
>>>> 
>>>> -- Dr. Lorenzo Sponza
>>>> Chargé de Recherche au CNRS
>>>> Laboratoire d'étude de microstructures (LEM), CNRS-ONERA
>>>> 29 Avenue de la division Leclerc, 92322 Châtillon
>>>> Tel: +33146734464
>>>> 
>>>> _______________________________________________
>>>> 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
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>>>> users mailing list users at lists.quantum-espresso.org
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>> -- 
>> Dr. Lorenzo Sponza
>> Chargé de Recherche au CNRS
>> Laboratoire d'étude de microstructures (LEM), CNRS-ONERA
>> 29 Avenue de la division Leclerc, 92322 Châtillon
>> Tel: +33146734464
>> _______________________________________________
>> 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 users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
> 
> -- 
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 206, 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 users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users