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<p>Hello,</p>
<p>when studying the similar compoiunf Ce2O2S, I only had good
results usign the high-precision Ce pseudopotential
Ce.pbe-spdfn-rrkjus_psl.1.0.0.UPF from the pslibrary that includes
5s5p6s4d5d4f in valence (22 electrons in valence) and requires a
ridiculous 200 Ry cutoff to converge, despite being Ultrasoft. The
U was almost 7eV. You can find more details in this paper and its
supplementary materials :
<a class="moz-txt-link-freetext" href="https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.9b00450">https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.9b00450</a> (I can
send the inout files if you want)</p>
<p>hth<br>
</p>
<div class="moz-cite-prefix">On 29/06/2025 18:55, AISWARYA CHANDRAN
via users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAHGUDAMJqEdVfXdzWuepSPA9En_cw4xQF2X0paTfhK79s8tsDQ@mail.gmail.com">
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<div>Dear Quantum ESPRESSO developers and users,<br>
<br>
I am working on Ce₂O₃ and trying to reproduce the
experimentally reported band gap (~2.4–2.7 eV) using LDA+U
in combination with spin–orbit coupling (SOC) in Quantum
ESPRESSO. However, despite using U = 6 eV and including SOC
via fully relativistic pseudopotentials, the computed band
gap is significantly underestimated (around 1.1 eV).<br>
<br>
Here are the key points of my setup:<br>
<br>
- Code version: QE 7.X<br>
- Pseudopotential: Ce.pz-spdfn-rrkjus_psl.1.0.0.UPF (fully
relativistic)<br>
- Functional: PZ-LDA<br>
- Hubbard_U applied: U = 6.0 eV on Ce 4f<br>
- Calculation type: SCF → bands<br>
<br>
- Structure: 5-atom primitive cell from literature (a = 3.87
Å, c/a = 1.522)<br>
- `nbnd = 41`<br>
- Gap is computed using `bands.x` and visual inspection<br>
<br>
Despite these, the gap remains ~1.1 eV. Literature reports
higher values for similar setups. I also observe that
relaxing the cell via `vc-relax` makes the lattice smaller,
which further reduces the gap. Using experimental lattice
constants does help, but not enough to reach the expected
values.<br>
<br>
Could you please advise on:<br>
1. Whether this pseudopotential is appropriate for SOC +
LDA+U calculations on Ce?<br>
2. Any suggestions on correcting the band gap
underestimation?<br>
3. Whether a better suited pseudopotential or approach
(e.g., using GGA+U, HSE, etc.) is recommended? I am
attaching the input file</div>
<div>4. I tried the same with Ce.pz-spdn-rrkjus_psl.1.0.0.UPF
it gives band gap of 3.7 eV. shall i proceed with spdn?<br>
<br>
I would greatly appreciate your insights.<font
color="#888888"><br>
</font></div>
<font color="#888888">
<div><br>
</div>
</font></div>
<div><br>
</div>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">
<div dir="ltr"><font face="comic sans ms, sans-serif"
color="#6aa84f"><b
style="background-color:rgb(255,255,255)">Thanks and
with Regards, </b></font>
<div><font face="comic sans ms, sans-serif" color="#6aa84f"><b
style="background-color:rgb(255,255,255)">Aiswarya
Chandran</b></font></div>
<div><font face="comic sans ms, sans-serif" color="#6aa84f"><b
style="background-color:rgb(255,255,255)">Research
Scholar<br>
</b></font>
<div><font face="comic sans ms, sans-serif"
color="#6aa84f"><b
style="background-color:rgb(255,255,255)">Laboratory
for Advanced Materials and Applied Research<br>
</b></font></div>
<div><font face="comic sans ms, sans-serif"
color="#6aa84f"><b
style="background-color:rgb(255,255,255)">Department
of Chemistry</b></font></div>
<div><font face="comic sans ms, sans-serif"
color="#6aa84f"><b
style="background-color:rgb(255,255,255)">NIT
Calicut, Kerala, India, 673 601</b></font></div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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<div class="moz-signature">-- <br>
<small>Dr. Lorenzo Paulatto<br>
IR IMPMC - CNRS UMR 7590 / Sorbonne Université / MNHN <br>
phone: +33 (0)1 442 79822 / telegram: lpaulatto<br>
<a href="http://www.impmc.upmc.fr/~paulatto/"
class="moz-txt-link-freetext">http://www.impmc.upmc.fr/~paulatto/</a>
- <a href="https://anharmonic.github.io/"
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