<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">It seems to me that the input files you provide DO NOT give rise to flat bands. I tried to run them, since the calculations last after few seconds, and the band structure is not flat.<div class=""><br class=""></div><div class="">Another question is whether your calculation corresponds to what reported in the paper you mention. Indeed, if you look carefully, the calculation reported therein concerns a three dimensional structure, that is rather obscure to me (see the Brillouin zone path, k-points coordinates change along k_x, k_y and k_y whereas you correctly choose a one-dimensional path). </div><div class="">The paper reports a unit cell a=6.52 A, b=c=1.304 A, which does not correspond to a linear chain, because 5-atom linear chains are parallel to x (6.52 ~ 1.306 * 5), but along y and z they are only 1.3 A far apart. So, try to understand if you want to reproduce the results of the paper, or calculate the band structure of a linear carbon chain, whose (not flat!) band structure is NOT that reported in Fig. 1 of the mentioned paper.</div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 15 May 2015, at 06:27, Zeina Al-Dolami <<a href="mailto:zaldolam@email.uark.edu" class="">zaldolam@email.uark.edu</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Dear users and developers,<div class="">I posted the below question more than two weeks ago. However, I have not received any response. Any feedback or suggestion is greatly appreciated. Thanks in advance </div><div class=""><br class=""></div><div class="">Zeina <br class=""><div class="gmail_quote">---------- Forwarded message ----------<br class="">From:<span class="Apple-converted-space"> </span><b class="gmail_sendername">Zeina Al-Dolami</b><span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:zaldolam@email.uark.edu" class="">zaldolam@email.uark.edu</a>></span><br class="">Date: Tue, Apr 28, 2015 at 3:54 PM<br class="">Subject: flat band structure<br class="">To:<span class="Apple-converted-space"> </span><a href="mailto:pw_forum@pwscf.org" class="">pw_forum@pwscf.org</a><br class=""><br class=""><br class=""><div dir="ltr" class="">Dear <span style="" class="">Pwscf's developers and users,</span><div class=""><font class="">I have started using quantum espresso recently for my research that focuses on investigating the mechanical and electrical properties of carbon based materials. I ran several examples of wannier90-1.2 to gain more understanding and insight of what I need to consider when running simulations for quantum conductance. However, I have realized that I need to reproduce the band structures of carbon based materials that have been already published then move to using wannier90. I came across this paper <a href="http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3469647" target="_blank" class="">http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3469647</a><span class="Apple-converted-space"> </span>page242. It is basically a linear chain of 5 carbon atoms. Also, Accelrys Software, DMol programme, was used in this paper. I used the below scf and band files to reproduce the same band structure. However, the band structure that was produced contains flat bands only. I went through the pw-forum to find whether there was similar question or not. I found some discussions related to band structure and other suggestions that I have considered but no success, such as<span class="Apple-converted-space"> </span><a href="http://qe-forge.org/pipermail/pw_forum/2005-December/078012.html" target="_blank" class="">http://qe-forge.org/pipermail/pw_forum/2005-December/078012.html</a></font><span style="" class=""> . Would you please</span><font class=""> tell me what I missed in my calculations? It is worth to mention that I have tried to use the same parameters available in this paper in my simulation. Any suggestion and feedback is greatly appreciated. Apologies if my question seems trivial because I am still at the beginning and have no background in this field. Looking forward to hearing from you. Thanks in advance </font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">Zeina </font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">scf file </font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">&CONTROL</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>calculation = 'scf',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>restart_mode= 'from_scratch',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>verbosity = 'high'</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>pseudo_dir = '/pseudo',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>outdir = './',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>prefix = '5cc',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>tstress = .f.,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>tprnfor = .t.,</font></div><div class=""><font class="">/</font></div><div class=""><font class="">&SYSTEM</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>ibrav = 1,</font></div><div class=""><font class="">! a = 6.520,</font></div><div style="" class="">! b = 1.304,</div><div class=""><span style="" class="">! c = 1.304,</span></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>celldm(1) = 12.3210,</font></div><div class=""><span style="" class=""> <span class="Apple-converted-space"> </span>cosbc = 0.,</span></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>cosac = 0.,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>cosab = 0.,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>nat = 5,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>ntyp = 1,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>ecutwfc = 30.,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>ecutrho = 240.,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>occupations = 'smearing',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>smearing = 'cold',</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>degauss = 0.03,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>nspin = 1,</font></div><div class=""><font class="">/</font></div><div class=""><font class="">&ELECTRONS</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>mixing_beta = 0.4</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>electron_maxstep = 1000,</font></div><div class=""><font class=""> <span class="Apple-converted-space"> </span>conv_thr = 1.D-10,</font></div><div class=""><font class="">/</font></div><div class=""><font class="">ATOMIC_SPECIES</font></div><div class=""><font class="">C 12.0107 C.pbe-rrkjus.UPF</font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">ATOMIC_POSITIONS (angstrom)</font></div><div class=""><font class="">C 0.183 0.000000000 0.000000000</font></div><div class=""><font class="">C 1.489 0.000000000 0.000000000</font></div><div class=""><font class="">C 2.791 0.000000000 0.000000000</font></div><div class=""><font class="">C 4.093 0.000000000 0.000000000</font></div><div class=""><font class="">C 5.399 0.000000000 0.000000000</font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">K_POINTS {automatic}</font></div><div class=""><font class="">6 1 1 0 0 0 </font></div><div class=""><font class=""> </font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class=""><br class=""></font></div><div class=""><font class="">band file </font></div><div class=""><font class=""><div class="">&CONTROL</div><div class=""> <span class="Apple-converted-space"> </span>calculation = 'bands',</div><div class=""> <span class="Apple-converted-space"> </span>restart_mode= 'from_scratch',</div><div class=""> <span class="Apple-converted-space"> </span>verbosity = 'high'</div><div class=""> <span class="Apple-converted-space"> </span>pseudo_dir = '/pseudo',</div><div class=""> <span class="Apple-converted-space"> </span>outdir = './',</div><div class=""> <span class="Apple-converted-space"> </span>prefix = '5cc',</div><div class=""> <span class="Apple-converted-space"> </span>tstress = .f.,</div><div class=""> <span class="Apple-converted-space"> </span>tprnfor = .t.,</div><div class="">/</div><div class="">&SYSTEM</div><div class=""> <span class="Apple-converted-space"> </span>ibrav = 1,</div><div class="">! a = 6.520,</div><div class="">! b = 1.304,</div><div class="">! c = 1.304,</div></font><font class=""><div class=""> <span class="Apple-converted-space"> </span>celldm(1) = 12.3210,</div><div class=""> <span class="Apple-converted-space"> </span>cosbc = 0.,</div><div class=""> <span class="Apple-converted-space"> </span>cosac = 0.,</div><div class=""> <span class="Apple-converted-space"> </span>cosab = 0.,</div><div class=""> <span class="Apple-converted-space"> </span>nat = 5,</div><div class=""> <span class="Apple-converted-space"> </span>ntyp = 1,</div><div class=""> <span class="Apple-converted-space"> </span>ecutwfc = 30.,</div><div class=""> <span class="Apple-converted-space"> </span>ecutrho = 240.,</div><div class=""> <span class="Apple-converted-space"> </span>occupations = 'smearing',</div><div class=""> <span class="Apple-converted-space"> </span>smearing = 'cold',</div><div class=""> <span class="Apple-converted-space"> </span>degauss = 0.03,</div><div class=""> <span class="Apple-converted-space"> </span>nspin = 1,</div><div class="">/</div><div class="">&ELECTRONS</div><div class=""> <span class="Apple-converted-space"> </span>mixing_beta = 0.4</div><div class=""> <span class="Apple-converted-space"> </span>electron_maxstep = 1000,</div><div class=""> <span class="Apple-converted-space"> </span>conv_thr = 1.D-10,</div><div class="">! diag_full_acc = .true.</div><div class=""><br class=""></div><div class="">/</div><div class="">ATOMIC_SPECIES</div><div class="">C 12.0107 C.pbe-rrkjus.UPF</div><div class=""><br class=""></div><div class="">ATOMIC_POSITIONS (angstrom)</div><div class="">C 0.183 0.000000000 0.000000000</div><div class="">C 1.489 0.000000000 0.000000000</div><div class="">C 2.791 0.000000000 0.000000000</div><div class="">C 4.093 0.000000000 0.000000000</div><div class="">C 5.399 0.000000000 0.000000000</div><div class=""><br class=""></div><div class="">K_POINTS {crystal}</div><div class="">6</div><div class="">0.00000000 0.00000000 0.00000000 1.00000000</div><div class="">0.16666667 0.00000000 0.00000000 1.00000000</div><div class="">0.33333333 0.00000000 0.00000000 1.00000000</div><div class="">0.50000000 0.00000000 0.00000000 1.00000000</div><div class="">0.66666667 0.00000000 0.00000000 1.00000000</div><div class="">0.83333333 0.00000000 0.00000000 1.00000000</div><span class="HOEnZb"><font color="#888888" class=""><div class=""><br class=""></div></font></span></font></div><span class="HOEnZb"><font color="#888888" class=""><div class=""><font class=""> </font></div><div class="">--<span class="Apple-converted-space"> </span><br class=""><div class=""><div dir="ltr" class=""><span class=""><font color="#888888" class="">Zeina Al-Dolami<br class="">PhD Candidate<br class="">Microelectronics and Photonics Graduate Program<span class="Apple-converted-space"> </span><br class="">University of Arkansas<br class="">Fayetteville, AR 72701<br class="">Office: PHYS 244<br class="">Email:<span class="Apple-converted-space"> </span><a href="mailto:zaldolam@email.uark.edu" target="_blank" class="">zaldolam@email.uark.edu</a><a href="mailto:cxm075@email.uark.edu" target="_blank" class=""></a></font></span></div></div></div></font></span></div></div><br class=""><br clear="all" class=""><div class=""><br class=""></div>--<span class="Apple-converted-space"> </span><br class=""><div class="gmail_signature"><div dir="ltr" class=""><span class=""><font color="#888888" class="">Zeina Al-Dolami<br class="">PhD Candidate<br class="">Microelectronics and Photonics Graduate Program<span class="Apple-converted-space"> </span><br class="">University of Arkansas<br class="">Fayetteville, AR 72701<br class="">Office: PHYS 244<br class="">Email:<span class="Apple-converted-space"> </span><a href="mailto:zaldolam@email.uark.edu" target="_blank" class="">zaldolam@email.uark.edu</a><a href="mailto:cxm075@email.uark.edu" target="_blank" class=""></a></font></span></div></div></div></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; 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-- <br class=""><br class="">Giovanni Cantele, PhD<br class="">CNR-SPIN<br class="">c/o Dipartimento di Fisica<br class="">Universita' di Napoli "Federico II"<br class="">Complesso Universitario M. S. Angelo - Ed. 6<br class="">Via Cintia, I-80126, Napoli, Italy<br class="">e-mail: <a href="mailto:giovanni.cantele@spin.cnr.it" class="">giovanni.cantele@spin.cnr.it</a><br class="">Phone: +39 081 676910<br class="">Skype contact: giocan74<br class=""><br class="">ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" class="">http://www.researcherid.com/rid/A-1951-2009</a><br class="">Web page: <a href="http://people.na.infn.it/~cantele" class="">http://people.na.infn.it/~cantele</a><br class="">
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