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<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Dear Lorenzo,</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;"> </div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Hello.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Thank you so much for your explanation.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">I will follow your suggestions.</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;"> </div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Bests,</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;">Mahmoud</div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;"> </div>
<div style="font-size: 16px; font-family: Tahoma; color: rgb(0, 0, 0); font-weight: 400; font-style: normal;"> </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: Lorenzo Paulatto <paulatz@gmail.com><br />
To: Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org><br />
Date: Sun, 21 Feb 2021 20:18:09 +0100<br />
Subject: Re: [QE-users] HOMO is higher than LUMO<br />
<div>Hello,</div>
<div>this happens when the system is a bad metal, with a pocket of valence electrons in a small Fermi surface. I.e., at some point in the Brillouin zone, the n-th band is lower in energy than the (n-1)-th band somewhere else, but these two bands do not touch. Just use a smearing for occupation and you'll solve the issue. Do not forget to recheck k-points convergence in the new case.</div>
<div>regards</div>
<div><signature id="local-80497166-1ed1">--<br />
<span style="font-size:0.9em;color:gray;">Lorenzo Paulatto - Paris</span></signature></div>
<div class="gmail_quote_attribution">On Feb 21 2021, at 7:05 pm, Mahmoud Payami Shabestari <mpayami@aeoi.org.ir> wrote:</div>
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<div><font style="font-size:16px"><font style="font-family:Tahoma">Dear QE-users/Developers,</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma"> </font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">In DFT+U calculation of an AFM pure system, I used an input file in which I had not used "occupation" card, but only a few bands more than half of the number of electrons. Then, the SCF run was successful, and in the output I get both HOMO and LUMO values correctly aligned, i.e., E_LUMO > E_HOMO.</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">However, when I add a metallic impurity (without changing the other parameters), the SCF run successfuly ends and in the output now I get E_HOMO > E_LUMO (!!).</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">I do not know how to interpret this result. Is there any miscalculation?</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">Any comments is highly appreciated.</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma"> </font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">Best regards,</font></font></div>
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<div><font style="font-size:16px"><font style="font-family:Tahoma">Mahmoud Payami</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">AEOI, Tehran, Iran</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma"> </font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">Email: mpayami@aeoi.org.ir</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma">Phone: +98 (0)21 82066504</font></font></div>
<div><font style="font-size:16px"><font style="font-family:Tahoma"> </font></font></div>
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