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<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Hi.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">DFT+U results in meta-stable states and careful analysis is needed for determining the true GS.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Please look at the paper : <a href="https://arxiv.org/pdf/2108.12758.pdf">https://arxiv.org/pdf/2108.12758.pdf</a></div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">which maybe useful.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">HTH</div>
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<div style="font-family: Tahoma; color: rgb(0, 0, 0); font-size: 16px; font-weight: 400; font-style: normal;">Mahmoud Payami</div>
<div style="font-family: Tahoma; color: rgb(0, 0, 0); font-size: 16px; font-weight: 400; font-style: normal;">NSTRI, AEOI, Tehran, Iran</div>
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<div style="font-family: Tahoma; color: rgb(0, 0, 0); font-size: 16px; font-weight: 400; font-style: normal;">Email: mpayami@aeoi.org.ir</div>
<div style="font-family: Tahoma; color: rgb(0, 0, 0); font-size: 16px; font-weight: 400; font-style: normal;">Phone: +98 (0)21 82066504</div>
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<blockquote class="as91pFk8AX8sDPOUp66RUy8IoCRjefxNG8oLk8fg" style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">From: Jhon Gonzalez <jhon.gonzalez@usm.cl><br />
To: "users@lists.quantum-espresso.org" <users@lists.quantum-espresso.org><br />
Date: Sun, 10 Oct 2021 23:36:57 +0000<br />
Subject: [QE-users] Hubbard-U QE vs VASP<br />
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<div>Hi,</div>
<div> </div>
<div><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Perhaps this is a bit off-topic, </span><font color="#000000"><span style="caret-color: rgb(0, 0, 0);">there is an issue when comparing LDA+U results in 2D-materials between Quantum-ESPRESSO and VASP.</span></font></div>
<div>For V2C monolayers, CrI3 mono- and bi-layers, the magnetic <span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">stability </span>changes and it is impossible to reproduce the results.</div>
<div> </div>
<div>For the V2C monolayer with U = 4 eV, while with quantum-ESPRESSO (US and PBE), I find that the ground-state </div>
<div>(GS) solution is FM and the AF solution is about 1 eV above; with VASP U=4 eV (LDATYPE=2), I find that the GS solution </div>
<div>is AF and the FM state is 1 eV above (in agreement with <a href="http://dx.doi.org/10.1021/jp507336x"> dx.doi.org/10.1021/jp507336x</a>). </div>
<div> </div>
<div>
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Following the discussion on the implementation of Hubbard's interaction: <a href="https://lists.quantum-espresso.org/pipermail/users/2020-May/044521.html">https://lists.quantum-espresso.org/pipermail/users/2020-May/044521.html</a></div>
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">There, it is suggested that in QE the Hubbard-U tends to decrease the gap, while in VASP it tends to open it.</div>
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<div>And inspired by the discussion <a href="http://grandcentral.apam.columbia.edu:5555/tutorials/dft_procedures/linear_response_u/index.html"> http://grandcentral.apam.columbia.edu:5555/tutorials/dft_procedures/linear_response_u/index.html</a> </div>
<div>there they mention an "empirically is a difference in sign convention". I tried a VASP calculation with U = -4 eV, and I found an </div>
<div>FM GS-solution followed by an AF solution 0.3 eV above, following the QE stability order.</div>
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<div> </div>
<div>From my experience comparing QE results with CrI3 experiments, it seems that QE uses the proper sign convention for the U term. </div>
<div>However, I do not have any evidence for this.</div>
<div> </div>
<div>I am currently exploring the use of hybrid functionals to address this issue, is there an elegant way to settle this dispute?</div>
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<div>Best,</div>
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