[QE-users] Collapse of 316L stainless steel structure

[Lorenzo Paulatto]

A bad pseudopotential could explain such an extreme behavior, where did 
you get them? And, can you share the output of the calculation?


On 04/02/2026 19:45, Yuvam Bhateja via users wrote:
> Dear Giuseppe,
>
> Thank you very much for your email. I tried your suggestion but 
> instead of a high number of 90 Ry and 1080 Ry as wfc and rho cutoff I 
> used 60 Ry and 480 Ry as a tradeoff while simulating Fe supercell with 
> a few perturbed atoms. Upon relaxation they returned to their 
> unperturbed positions. I hope it shoes work with the alloy structure 
> too, Do I need to use a more denser grid for a better relaxation 
> calculation?
>
> Thanks
> Yuvam
> ------------------------------------------------------------------------
> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of 
> giuseppe.mattioli at mlib.ism.cnr.it <giuseppe.mattioli at mlib.ism.cnr.it>
> *Sent:* Monday, February 2, 2026 2:57 PM
> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
> *Subject:* Re: [QE-users] Collapse of 316L stainless steel structure
>
> Dear Yuvam Bhateja
> Your input file seems correct. I can only suppose that you are using a
> badly unconverged ecutwfc. In a Fe supercell you start from highly
> symmetric atomic positions, so that forces on ions are symmetrized too
> and can't break initial symmetry. When you break the symmetry inserting
> Cr and Ni, then forces are not symmetrized anymore and are affected by
> the low ecutwfc value problem. the SSSP efficiency database suggest an
> ecutwfc value of 90 Ry for Fe PAW of the 0.3.1 atomic database, with a
> tremendous ecutrho of 1080 Ry... You may try to slightly randomize the
> position of Fe atoms in your all-Fe supercell to see if they recover
> their initial positions or go astray.
>
> Gamma-only might be a too limited sampling of the 1BZ for a metal, too,
> but this should be a secondary problem.
> HTH
> Giuseppe
>
> Il 2026-02-02 14:07 Yuvam Bhateja via users ha scritto:
> > Greetings,
> >
> >  I am trying to simulate 316L stainless steel structure with the FCC
> > Fe unit cell as the base. My system has total 108 atoms and I have
> > replaced Fe with Ni and Cr to match the composition of 316L steel.
> >
> >  I have structurally optimized my Fe supercell before making the
> > substitution. Everything is in order, however, my 316L keep collapsing
> > inwards. Both relax and vc-relax is causing the same issue. It is not
> > retaining the cuboidal shape but becoming distorted (towards becoming
> > a sphere). I have tried different kinds of pseudopotentials: PBE,
> > PBEsol with either PAW or USPP (NCSR). All of them are working for Fe
> > supercell but none on the steel. I have tried to make the substitution
> > fairly random and homogeneous.
> >
> >  Can someone suggest what can I do to achieve a stable structure? I am
> > attaching the input file and a snapshot of the relaxed structure.
> >
> >  Thanks
> >  Yuvam Bhateja
> >  Department of Chemistry, Materials and Chemical Engineering "Giulio
> > Natta"
> >  Politecnico Di Milano
> > 
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Dr. Lorenzo Paulatto
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