<div dir="auto">Thank you for the reply.<div dir="auto"><br></div><div dir="auto">I am not sure how to solve this problem.</div><div dir="auto">I tried using different pseudopotentials with diffrent XC. Even tried increasing U value.</div><div dir="auto"><br></div><div dir="auto">In most of the papers, pure bulk Cr2O3 is used.</div><div dir="auto"><br></div><div dir="auto">Can you please advise me?</div><div dir="auto"><br></div><div dir="auto">Thank you in advance.</div><div dir="auto"><br></div><div dir="auto">Regards</div><div dir="auto">Yuvam</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 23 Jul 2020, 6:08 pm Nicola Marzari, <<a href="mailto:nicola.marzari@epfl.ch">nicola.marzari@epfl.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
<br>
Indeed! Although I would feel better about using as Fermi energy the <br>
zero temperature limit of the chemical potential, that would be <br>
(homo+lumo)/2? (well, the band edges).<br>
<br>
nicola<br>
<br>
PS: of course the lumo is wrong even in exact DFT, and the homo is <br>
correct only in exact DFT, and wrong in approximate DFT.<br>
<br>
On 23/07/2020 14:35, Pietro Delugas wrote:<br>
> Dear Yuvam<br>
> <br>
> When one uses smeared occupations in systems with a large gap ( <br>
> significantly larger than the smearing) the final value of the Fermi <br>
> level returned from the calculation may be any value within the band gap <br>
> sufficiently far from the band edges (HOMO and LUMO). All the values <br>
> in this range yield the same values for the occupations and thus of the <br>
> ground state density. If you wish you can decide to follow the <br>
> convention of the other papers and refer to the HOMO as the Fermi level.<br>
> <br>
> In fact in insulators the thermodynamic Fermi level depends on extrinsic <br>
> conditions such as doping or defect concentrations and on the <br>
> temperature. All things which are obviously not taken into account in <br>
> your calculation.<br>
> <br>
> Kind regards<br>
> <br>
> Pietro<br>
> <br>
> Sent from Mail <<a href="https://go.microsoft.com/fwlink/?LinkId=550986" rel="noreferrer noreferrer" target="_blank">https://go.microsoft.com/fwlink/?LinkId=550986</a>> for <br>
> Windows 10<br>
> <br>
> *From: *Yuvam Bhateja <mailto:<a href="mailto:yuvamb16@gmail.com" target="_blank" rel="noreferrer">yuvamb16@gmail.com</a>><br>
> *Sent: *Thursday, July 23, 2020 12:44 PM<br>
> *To: *Quantum ESPRESSO users Forum <mailto:<a href="mailto:users@lists.quantum-espresso.org" target="_blank" rel="noreferrer">users@lists.quantum-espresso.org</a>><br>
> *Subject: *[QE-users] Wrong position of fermi level in bulk Cr2O3<br>
> <br>
> Hello dear experts,<br>
> <br>
> Hope you are doing well.<br>
> <br>
> I was trying to calculate the DOS in hexagonal Cr2O3, the DOS is coming <br>
> very well with a bandgap of 3.09, but the problem is the Fermi level is <br>
> at the edge of LUMO whereas I've observed that it should be at HUMO edge <br>
> in few already published papers.<br>
> <br>
> I used PBE NC SR pseudopotential and also optimized with the same. I <br>
> used gaussian smearing with a width of 0.001 in VC-relax and tetrahedra <br>
> in SCF calculation.<br>
> <br>
> Here is my input file -<br>
> <br>
> &CONTROL<br>
> calculation = "scf"<br>
> pseudo_dir = "./"<br>
> outdir = "./outdir"<br>
> /<br>
> <br>
> &SYSTEM<br>
> a = 4.6166825e+00<br>
> c = 1.2457778e+01<br>
> ecutrho = 4.5000e+02<br>
> ecutwfc = 4.5000e+01<br>
> ibrav = 4<br>
> nat = 30<br>
> nspin = 2<br>
> ntyp = 3<br>
> nbnd = 276<br>
> starting_magnetization(1) = 0.5<br>
> starting_magnetization(2) = -0.5<br>
> starting_magnetization(3) = 0.0<br>
> tot_magnetization = 0.0<br>
> lda_plus_u = .true.<br>
> Hubbard_U(1) = 4.7<br>
> Hubbard_U(2) = 4.7<br>
> Hubbard_J0(1) = 1<br>
> Hubbard_J0(2) = 1<br>
> /<br>
> <br>
> &ELECTRONS<br>
> conv_thr = 1.00000e-11<br>
> electron_maxstep = 2000<br>
> mixing_beta = 7.00000e-01<br>
> startingpot = "atomic"<br>
> startingwfc = "atomic+random"<br>
> /<br>
> <br>
> <br>
> K_POINTS {automatic}<br>
> 12 12 12 0 0 0<br>
> <br>
> ATOMIC_SPECIES<br>
> Cr1 51.99610 Cr.upf<br>
> Cr2 51.99610 Cr.upf<br>
> O 15.99940 O.upf<br>
> <br>
> ATOMIC_POSITIONS (angstrom)<br>
> Cr2 -0.0000027528 2.6654550870 3.9638155751<br>
> Cr1 2.3083528721 1.3327252495 2.2651020880<br>
> Cr1 -0.0000027528 2.6654550870 0.1887989665<br>
> Cr2 0.0000000000 0.0000000000 1.8875092202<br>
> Cr2 0.0000000000 0.0000000000 8.1164268017<br>
> Cr1 -0.0000027528 2.6654550870 6.4177165986<br>
> Cr1 0.0000000000 -0.0000000000 4.3414084067<br>
> Cr2 2.3083528721 1.3327252495 6.0401185402<br>
> Cr2 2.3083528721 1.3327252495 12.2690363475<br>
> Cr1 0.0000000000 0.0000000000 10.5703258606<br>
> Cr1 2.3083528721 1.3327252495 8.4940197683<br>
> Cr2 -0.0000027528 2.6654550870 10.1927331413<br>
> O 1.4445126756 0.0000000398 3.1144588851<br>
> O 3.0306076646 0.0817435268 1.0381518347<br>
> O 0.8638388763 1.3327251470 1.0381518347<br>
> O 3.0306056520 2.5837116627 1.0381518347<br>
> O -0.7222568310 1.2509851988 3.1144588851<br>
> O 1.5860942747 2.7471960155 3.1144588851<br>
> O 3.7528623252 1.3327254382 7.2670694393<br>
> O 0.7222547656 1.4144695631 5.1907658203<br>
> O -1.4445122603 2.6654550733 5.1907658203<br>
> O 0.7222574947 3.9164369542 5.1907658203<br>
> O 1.5860961469 2.5837115564 7.2670694393<br>
> O 1.5860937210 0.0817433419 7.2670694393<br>
> O 1.4445122976 2.6654551364 11.4196834856<br>
> O -1.5860942579 2.7471959172 9.3433763434<br>
> O 0.8638382678 3.9981804108 9.3433763434<br>
> O 0.7222569078 1.2509852624 9.3433763434<br>
> O -0.7222575680 3.9164369549 11.4196834856<br>
> O -0.7222547296 1.4144694992 11.4196834856<br>
> <br>
> I later tried with pw91 USPP, it fixed the fermi level position (it's <br>
> now at HUMO edge) but the bad gap is now very underestimated to 2.3 eV.<br>
> <br>
> I tried paw but it wasn't working with me.<br>
> <br>
> Can someone please help?<br>
> <br>
> Regards<br>
> <br>
> Yuvam Bhateja<br>
> <br>
> IIEST Shibpur<br>
> <br>
> India<br>
> <br>
> <br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" rel="noreferrer noreferrer" target="_blank">www.max-centre.eu/quantum-espresso</a>)<br>
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> <br>
<br>
<br>
-- <br>
----------------------------------------------------------------------<br>
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL<br>
Director, National Centre for Competence in Research NCCR MARVEL, EPFL<br>
<a href="http://theossrv1.epfl.ch/Main/Contact" rel="noreferrer noreferrer" target="_blank">http://theossrv1.epfl.ch/Main/Contact</a> <a href="http://nccr-marvel.ch/en/project" rel="noreferrer noreferrer" target="_blank">http://nccr-marvel.ch/en/project</a><br>
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