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Dear Giuseppe,</div>
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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? </div>
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Thanks</div>
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Yuvam</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of giuseppe.mattioli@mlib.ism.cnr.it <giuseppe.mattioli@mlib.ism.cnr.it><br>
<b>Sent:</b> Monday, February 2, 2026 2:57 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org><br>
<b>Subject:</b> Re: [QE-users] Collapse of 316L stainless steel structure</font>
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Dear Yuvam Bhateja<br>
Your input file seems correct. I can only suppose that you are using a <br>
badly unconverged ecutwfc. In a Fe supercell you start from highly <br>
symmetric atomic positions, so that forces on ions are symmetrized too <br>
and can't break initial symmetry. When you break the symmetry inserting <br>
Cr and Ni, then forces are not symmetrized anymore and are affected by <br>
the low ecutwfc value problem. the SSSP efficiency database suggest an <br>
ecutwfc value of 90 Ry for Fe PAW of the 0.3.1 atomic database, with a <br>
tremendous ecutrho of 1080 Ry... You may try to slightly randomize the <br>
position of Fe atoms in your all-Fe supercell to see if they recover <br>
their initial positions or go astray.<br>
<br>
Gamma-only might be a too limited sampling of the 1BZ for a metal, too, <br>
but this should be a secondary problem.<br>
HTH<br>
Giuseppe<br>
<br>
Il 2026-02-02 14:07 Yuvam Bhateja via users ha scritto:<br>
> Greetings,<br>
> <br>
> I am trying to simulate 316L stainless steel structure with the FCC<br>
> Fe unit cell as the base. My system has total 108 atoms and I have<br>
> replaced Fe with Ni and Cr to match the composition of 316L steel.<br>
> <br>
> I have structurally optimized my Fe supercell before making the<br>
> substitution. Everything is in order, however, my 316L keep collapsing<br>
> inwards. Both relax and vc-relax is causing the same issue. It is not<br>
> retaining the cuboidal shape but becoming distorted (towards becoming<br>
> a sphere). I have tried different kinds of pseudopotentials: PBE,<br>
> PBEsol with either PAW or USPP (NCSR). All of them are working for Fe<br>
> supercell but none on the steel. I have tried to make the substitution<br>
> fairly random and homogeneous.<br>
> <br>
> Can someone suggest what can I do to achieve a stable structure? I am<br>
> attaching the input file and a snapshot of the relaxed structure.<br>
> <br>
> Thanks<br>
> Yuvam Bhateja<br>
> Department of Chemistry, Materials and Chemical Engineering "Giulio<br>
> Natta"<br>
> Politecnico Di Milano<br>
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