<div dir="ltr"><div>Hi,</div><div>I already gave a few hints in the previous message. Generally speaking, what always works (and is quite important especially for students)</div><div>is the "try by yourself" recipe. When help is given, then the answer to the raised question is important to eventually go further.</div><div><br></div><div>1) As said in the previous message, did you check that you are displaying the right energy window and not bands much below or much above the Fermi energy? </div><div><br></div><div>2) As said in the previous message, did you check your input structure? The point here is that if you do it by yourself, you can use all the patience it takes to</div><div>find out possible mistakes. If others do it for you, they for sure will do it very quickly! I did it for you very quickly, provided I made no mistakes (which is up to you to check!), it seems to me that</div><div>if you are comparing with MgC2 structure reported here: <a href="https://pubs.rsc.org/en/content/articlepdf/2025/cp/d5cp00253b" target="_blank">https://pubs.rsc.org/en/content/articlepdf/2025/cp/d5cp00253b</a> there are anything but negligible differences, which might</div><div>cause in turn differences in the band structure: i) bond length therein is 2.14 A, Mg-C bond I measure here is 2.823 A, is it correct? If so a 0.7 A difference would correspond to</div><div>> 30% strain, which can turn your structure from metallic to semiconducting, from semiconducting to metallic or even destroy it!</div><div>Moreover, the "height" therein is 2.46 A, here it seems 2.14 A (calculated as z_Mg - z_C). Is this correct?</div><div><br></div><div>3) this has minor (or no) impact on your calculation, but if you expect an hexagonal lattice, a1 and a2 should have exactly the same length (and I would use the specific ibrav, not ibrav=1).</div><div>Also, for a perfect hexagonal lattice the x and y coordinates of K point you chose (if correct!) must be exactly the same. </div><div><br></div><div>No other hint can be given, before you are pretty sure that, apart from DFT code and basis set, you are investigating exactly the same structure.</div><div><br></div><div>Just as a side (and useless) notice, the band structure reported in Fig. 1 of that paper has been drawn with very few points, that would be acceptable only if the calculation would have been</div><div>very expensive (which is not the case of a monolayer). Should I had been a reviewer, I would have discouraged publication of such a rough plot!</div><div>Giovanni</div><div><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><span style="color:rgb(0,0,0)">-- <br><br>Prof. Giovanni Cantele<br>Dipartimento di Fisica "Ettore Pancini"<br>Universita' degli Studi di Napoli "Federico II"<br>Complesso Universitario M. S. Angelo - Ed. 6<br>Via Cintia, I-80126, Napoli, Italy<br>e-mail: giovanni.cantele@unina<br>Phone: +39 081 676910<br><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 mar 30 set 2025 alle ore 12:23 Jodan Ebaya <<a href="mailto:jpebaya@carsu.edu.ph" target="_blank">jpebaya@carsu.edu.ph</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">Good day everyone!<div dir="auto"><br></div><div dir="auto">Thank you Dr. Giovanni Cantele and Dr. Nicola Marzari.</div><div dir="auto"><br></div><div dir="auto">And regarding to the trials i've done, i use cutoff ( 60, 80, 90 and 100) From relax to plotting the band structure but still the i get zero band gap, Below is the latest nscf(bands) input file i have used. </div><div dir="auto"><br></div><div dir="auto"><div dir="auto">&control</div><div dir="auto"> calculation = 'nscf',</div><div dir="auto"> prefix = 'MgC2',</div><div dir="auto"> outdir = './tmp/',</div><div dir="auto"> pseudo_dir = './pseudo/',</div><div dir="auto">/</div><div dir="auto">&system</div><div dir="auto"> ibrav = 0,</div><div dir="auto"> nat = 3, </div><div dir="auto"> ntyp = 2,</div><div dir="auto"> nbnd = 20,</div><div dir="auto"> ecutwfc = 120,</div><div dir="auto"> ecutrho = 1200,</div><div dir="auto"> input_dft = 'PBE',</div><div dir="auto"> occupations = 'fixed',</div><div dir="auto">/</div><div dir="auto">&electrons</div><div dir="auto"> conv_thr = 1.0d-8,</div><div dir="auto">/</div><div dir="auto">ATOMIC_SPECIES</div><div dir="auto">Mg 24.30500 Mg.pbe-spnl-kjpaw_psl.0.3.0.UPF</div><div dir="auto">C 12.01100 C.pbe-n-kjpaw_psl.1.0.0.UPF</div><div dir="auto"><br></div><div dir="auto">ATOMIC_POSITIONS {crystal}</div><div dir="auto">Mg 0.000000000 0.000000000 0.440789640</div><div dir="auto">C 0.332488607 0.664978213 0.547855180</div><div dir="auto">C 0.667511393 0.335021787 0.547855180</div><div dir="auto"><br></div><div dir="auto">CELL_PARAMETERS {angstrom}</div><div dir="auto"> 3.181000 0.000000 0.000000</div><div dir="auto"> -1.590500 2.758000 0.000000</div><div dir="auto"> 0.000000 0.000000 20.000000</div><div dir="auto"><br></div><div dir="auto">K_POINTS crystal_b</div><div dir="auto"> 4</div><div dir="auto"> 0.00000 0.00000 0.00000 40 ! Gamma</div><div dir="auto"> 0.50000 0.00000 0.00000 40 ! M</div><div dir="auto"> 0.33372 0.33314 0.00000 40 ! K</div><div dir="auto"> 0.00000 0.00000 0.00000 0 ! Gamma</div><div dir="auto"><br></div><div dir="auto">Any correction and suggestions are greatly appreciated. Thank you and Godbless everyone.</div><div dir="auto"><br></div><div dir="auto">Sincerely,</div><div dir="auto"><br></div><div dir="auto">Jordan Lee P. Ebaya</div><div dir="auto">MS-Physics Student</div><div dir="auto">Mindanao State University</div><div dir="auto">Iligan Institute of Technology</div><div dir="auto">Iligan City, Philippines</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div></div></div>
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