<div dir="ltr">Dear Dr.<span style="color:rgb(0,0,0)">Giovanni Cantele,</span><div><font color="#000000">Thanks for your reply, I'm using the DFT + U method for calculations. I'm following the materials project site as the base reference for the structure. that bandgap value was obtained from the references that follow the hybrid density functional method. I have attached the SCF and band calculation inputs file below. Can please check these input files.</font></div><div><font color="#000000"><br></font></div><div><font color="#000000">Thank you,</font></div><div><font color="#000000"><br></font></div><div>&CONTROL<br> calculation = 'scf',<br> restart_mode = 'from_scratch',<br> prefix = 'bands',<br> outdir = './tmp/'<br> pseudo_dir = './psuedo_sr'<br> verbosity = 'high'<br>/<br><br>&SYSTEM<br> ibrav = 4, <br> a = 5.14011, c = 13.82966,<br> cosBC = 0,<br> cosAC = 0,<br> cosAB = -0.5, <br> nat = 30, ntyp = 4,<br> ecutwfc = 50,<br> ecutrho = 400.0,<br> nbnd = 280<br> occupations = 'smearing', degauss = 0.001, smearing = 'gaussian',<br> nspin=2,<br> starting_magnetization(1) = 4<br> starting_magnetization(2) = -4<br> starting_magnetization(3) = 0<br> starting_magnetization(4) = 0<br>/<br><br>&electrons<br> conv_thr = 1.0e-7<br> electron_maxstep = 500<br> mixing_beta = 0.3d0<br>/<br><br>ATOMIC_SPECIES<br> Fe1 55.845 Fe.pbe-spn-kjpaw_psl.1.0.0.UPF<br> Fe2 55.845 Fe.pbe-spn-kjpaw_psl.1.0.0.UPF<br> Ti 47.867 Ti.pbe-spn-kjpaw_psl.1.0.0.UPF<br> O 15.999 O.pbe-n-kjpaw_psl.1.0.0.UPF<br><br>ATOMIC_POSITIONS (crystal)<br>Ti 0.333333671 0.666666687 0.019728789<br>Ti 0.333333671 0.666666687 0.313609332<br>Ti 0.000000000 0.000000000 0.353068292<br>Ti 0.000000000 0.000000000 0.646931648<br>Ti 0.666667104 0.333333343 0.686390758<br>Ti 0.666667104 0.333333343 0.980271161<br>Fe1 0.000000000 0.000000000 0.141661420<br>Fe2 0.666667104 0.333333343 0.191701844<br>Fe2 0.666667104 0.333333343 0.474968076<br>Fe1 0.333333671 0.666666687 0.525031984<br>Fe1 0.333333671 0.666666687 0.808297873<br>Fe2 0.000000000 0.000000000 0.858338833<br>O 0.679246187 0.972118676 0.254297256<br>O 0.027881473 0.707126856 0.254297256<br>O 0.292873383 0.320754439 0.254297256<br>O 0.987438619 0.361118644 0.079032004<br>O 0.373680741 0.012561911 0.079032004<br>O 0.638881803 0.626319408 0.079032004<br>O 0.345913947 0.305455208 0.587620795<br>O 0.694545090 0.040458456 0.587620795<br>O 0.959542215 0.654086351 0.587620795<br>O 0.654086947 0.694544613 0.412379205<br>O 0.040458292 0.345913559 0.412379205<br>O 0.305455744 0.959541857 0.412379205<br>O 0.012562054 0.638881326 0.920967937<br>O 0.361118942 0.373680562 0.920967937<br>O 0.626320004 0.987438083 0.920967937<br>O 0.320754468 0.027881414 0.745702744<br>O 0.707127631 0.679245710 0.745702744<br>O 0.972119093 0.292872876 0.745702744<br><br>K_POINTS (automatic)<br>7 7 3 0 0 0<br>HUBBARD (atomic)<br> U Fe1-3d 5.3<br> U Fe2-3d 5.3</div><div><br></div><div>best regards</div><div>Prasad Sankalpa</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Feb 16, 2024 at 4:06 PM Giovanni Cantele <<a href="mailto:giovanni.cantele@spin.cnr.it">giovanni.cantele@spin.cnr.it</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Dear <br clear="all"><div><div dir="ltr" class="gmail_signature"><div dir="ltr"><span style="color:rgb(0,0,0)">Prasad, there are not sufficient data to understand what's happening.</span></div><div dir="ltr"><span style="color:rgb(0,0,0)"><br></span></div><div><span style="color:rgb(0,0,0)">1) DFT systematically underestimates band gaps, to what extent depends on the material. If this is the case there is nothing to do unless moving to</span></div><div><span style="color:rgb(0,0,0)">other approximations that at least partially solve this problem (DFT+U,hybrid functionals,GW,....)</span></div><div><span style="color:rgb(0,0,0)">2) do the references you mention concern theoretical estimations within DFT or experimental data? While when comparing with experiments you</span></div><div><span style="color:rgb(0,0,0)">might experient the limit of the previous point, whereas if you find other calculations, within the same level of approximation, you should find at least</span></div><div><span style="color:rgb(0,0,0)">similar (if not equal) results</span></div><div><span style="color:rgb(0,0,0)">3) in the case you have reference calculations to compare with and there is no agreement, check your input geometry and unit cell (to understand if they</span></div><div><span style="color:rgb(0,0,0)">are wrong) as well as the convergence parameters (Brillouin zone sampling, wave function cutoff, charge density cutoff if it applies, ....)</span></div><div><span style="color:rgb(0,0,0)"><br></span></div><div><span style="color:rgb(0,0,0)">Giovanni</span></div><div dir="ltr"><span style="color:rgb(0,0,0)"><br></span></div><div dir="ltr"><span style="color:rgb(0,0,0)">-- <br><br>Giovanni Cantele, PhD<br>CNR-SPIN<br>c/o Dipartimento di Fisica<br>Universita' di Napoli "Federico II"<br>Complesso Universitario M. S. Angelo - Ed. 6<br>Via Cintia, I-80126, Napoli, Italy<br><a href="mailto:giovanni.cantele@spin.cnr.it" style="color:rgb(17,85,204)" target="_blank">e-mail: giovanni.cantele@spin.cnr.it</a><br>Phone: +39 081 676910<br>Skype contact: giocan74<br><br>ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" style="color:rgb(17,85,204)" target="_blank">http://www.researcherid.com/rid/A-1951-2009</a><br>Web page: </span><a href="https://sites.google.com/view/giovanni-cantele/home" style="color:rgb(17,85,204)" target="_blank">https://sites.google.com/view/giovanni-cantele/home</a><br></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Il giorno ven 16 feb 2024 alle ore 10:40 PRASAD SANKALPA WANNINAYAKA <<a href="mailto:2019s17502@stu.cmb.ac.lk" target="_blank">2019s17502@stu.cmb.ac.lk</a>> ha scritto:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div class="gmail_quote" dir="auto">Dear QE users,<br><div dir="ltr">I am studying the electronic properties of FeTiO3 using QE when calculating the band structure using 'bands.x' calculation. I obtained the bandgap as 0.01eV but according to references that value is 2.54 eV. i need to know why this is happening. </div><div dir="ltr"><br></div><div dir="ltr">Thank you</div><div dir="ltr">Best regards</div><div dir="ltr">Prasad Sankalpa </div><div dir="ltr">Physics Undergraduate </div>
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