<div dir="ltr">Dear users and developers,<div>I have been using wannier90. v1.2 for a while. I have run many examples in the tutorial and other papers to make sure that I have good understanding. I have focused recently on CNT, graphene, and other carbon based materials as they are related to my research. However, I realize that I still face some issues sometimes that might be related to misunderstanding some concepts. </div><div><br></div><div>My first question is that why do I see straight bands (lines) when plotting the band structure of a system? Are these valance bands besides having the conduction bands? Is there a problem with the projections that I am choosing or the system itself? What can be the reason for having these bands as straight lines? </div><div><br></div><div>My second question is why does the quantum conductance plot has kind of spikes at specific energy values, while it has zero values at others? I understand it depends on the system, its electronic properties, etc. I tried to run the calculations for systems in published papers as a way to confirm mine. However, I do not get continuous values for the quantum conductance as the published ones when I run the calculations for the same system as theirs. Is it because of different methods of calculations? I am totally confused although I realize it is quantum conductance not classical conductance. Here is the link to one paper: Kindly, have a look at figure (4). <a href="http://www.ncbi.nlm.nih.gov/pubmed/21406839">http://www.ncbi.nlm.nih.gov/pubmed/21406839</a></div><div><br></div><div>Last question is there any formula that I can use to calculate the current from the quantum conductance? If so, what is it? I know that conductance and current are related, but I am not sure about the quantum conductance vs energy obtained using wannier90 codes. </div><div><br></div><div>Would you please help me with it? Any feedback and comments are greatly appreciated. My questions may seem to you viral and basics, but I need your help with them as I am working on something that I do not have the required background in it. Feel free to advice and suggest anything because I am willing to understand what I am doing. Apologies for the long email and many thanks in advance </div><div><br></div><div>I appreciate your time</div><div>Zeina </div><div><br></div><div><br></div><div>Below are my scf and win input files for a system on 16 carbon atoms forming a linear chain. Also, the attached file is an image that shows the quantum conductance. </div><div><br></div><div><br></div><div><b><font size="4"><a href="http://scf.in">scf.in</a> </font></b></div><div><div>&CONTROL</div><div> calculation = 'scf',</div><div> restart_mode= 'from_scratch',</div><div> verbosity = 'high'</div><div> pseudo_dir = '/share/apps/espresso/espresso-5.1/wannier90-1.2/pseudo',</div><div> outdir = './',</div><div> prefix = '16cc',</div><div> tstress = .f.,</div><div> tprnfor = .t.,</div><div>/</div><div>&SYSTEM</div><div> ibrav = 0,</div><div> cosbc = 0.,</div><div> cosac = 0.,</div><div> cosab = 0.,</div><div> nat = 16,</div><div> ntyp = 1,</div><div> ecutwfc = 30.,</div><div> ecutrho = 240.,</div><div> occupations = 'smearing',</div><div> smearing = 'gauss',</div><div> degauss = 0.03,</div><div> nspin = 1,</div><div>/</div><div>&ELECTRONS</div><div> mixing_beta = 0.4</div><div> electron_maxstep = 1000,</div><div> conv_thr = 1.D-10,</div><div>/</div><div>CELL_PARAMETERS {angstrom}</div><div> 20.458886621 0.000000000 0.000000000</div><div> 0.000000000 25.000000000 0.000000000</div><div> 0.000000000 0.000000000 25.000000000</div><div><br></div><div>ATOMIC_SPECIES</div><div>C 12.0107 C.pbe-rrkjus.UPF</div><div>ATOMIC_POSITIONS (angstrom)</div><div>C -14.491185639 2.648257939 0.505011814</div><div>C -13.212548441 2.639140677 0.504993925</div><div>C -11.934057148 2.631250135 0.505001124</div><div>C -10.655273151 2.628096695 0.504983717</div><div>C -9.376861524 2.629562369 0.505014056</div><div>C -8.098078606 2.636882829 0.504994802</div><div>C -6.819628629 2.647859469 0.504997196</div><div>C -5.541017166 2.657794809 0.505001284</div><div>C -4.262199583 2.666003307 0.505000350</div><div>C -2.983358631 2.674866294 0.504996410</div><div>C -1.704642031 2.682927649 0.505005747</div><div>C -0.425711088 2.686224288 0.504970561</div><div>C 0.852918441 2.684017937 0.504994114</div><div>C 2.131876861 2.677086156 0.504990800</div><div>C 3.410495116 2.666998386 0.505016462</div><div>C 4.689291674 2.657031063 0.505027639</div><div><br></div><div>K_POINTS {automatic}</div><div>8 1 1 0 0 0</div></div><div><br></div><div><br></div><div><b><font size="4"><a href="http://win.in">win.in</a></font></b></div><div><div>num_bands = 100</div><div>num_wann = 80</div><div>num_iter = 100</div><div><br></div><div>dis_num_iter = 100</div><div>dis_win_max = 8.0</div><div>dis_froz_max = 3.5</div><div>dis_froz_min = -8.0</div><div><br></div><div>guiding_centres = .true.</div><div><br></div><div>mp_grid = 8 1 1 </div><div><br></div><div>iprint = 2</div><div><br></div><div>num_dump_cycles = 100</div><div>num_print_cycles = 10</div><div><br></div><div>transport = true</div><div>transport_mode = bulk</div><div>one_dim_axis = x</div><div>dist_cutoff = 5.5</div><div>tran_win_min = -8.5</div><div>tran_win_max = 8.5</div><div>tran_energy_step = 0.01</div><div>fermi_energy = -5.0792</div><div>dist_cutoff_mode = one_dim</div><div>translation_centre_frac = 0.0 0.0 0.0</div><div><br></div><div>bands_plot = true</div><div>bands_plot_format = gnuplot</div><div>!search_shells = 50</div><div><br></div><div>begin kpoint_path</div><div>G 0.00000 0.00000 0.00000 F 0.12500 0.00000 0.00000</div><div>F 0.12500 0.00000 0.00000 Q 0.25000 0.00000 0.00000</div><div>Q 0.25000 0.00000 0.00000 Z 0.35000 0.00000 0.00000</div><div>Z 0.35000 0.00000 0.00000 W 0.50000 0.00000 0.00000</div><div>W 0.50000 0.00000 0.00000 B 0.75000 0.00000 0.00000</div><div>end kpoint_path</div><div><br></div><div>begin projections</div><div>C:sp3;pz</div><div>end projections</div><div><br></div><div>begin unit_cell_cart</div><div>Ang</div><div> 20.458886621 0.000000000 0.000000000</div><div> 0.000000000 25.000000000 0.000000000</div><div> 0.000000000 0.000000000 25.000000000</div><div>end unit_cell_cart</div><div><br></div><div>begin atoms_cart</div><div>Ang</div><div>C -14.491185639 2.648257939 0.505011814</div><div>C -13.212548441 2.639140677 0.504993925</div><div>C -11.934057148 2.631250135 0.505001124</div><div>C -10.655273151 2.628096695 0.504983717</div><div>C -9.376861524 2.629562369 0.505014056</div><div>C -8.098078606 2.636882829 0.504994802</div><div>C -6.819628629 2.647859469 0.504997196</div><div>C -5.541017166 2.657794809 0.505001284</div><div>C -4.262199583 2.666003307 0.505000350</div><div>C -2.983358631 2.674866294 0.504996410</div><div>C -1.704642031 2.682927649 0.505005747</div><div>C -0.425711088 2.686224288 0.504970561</div><div>C 0.852918441 2.684017937 0.504994114</div><div>C 2.131876861 2.677086156 0.504990800</div><div>C 3.410495116 2.666998386 0.505016462</div><div>C 4.689291674 2.657031063 0.505027639</div><div>end atoms_cart</div><div><br></div><div>Begin KPoints</div><div> 0.00000000 0.00000000 0.00000000 </div><div> 0.12500000 0.00000000 0.00000000 </div><div> 0.25000000 0.00000000 0.00000000 </div><div> 0.37500000 0.00000000 0.000800000 </div><div> 0.50000000 0.00000000 0.00000000 </div><div> 0.62500000 0.00000000 0.00000000 </div><div> 0.75000000 0.00000000 0.00000000 </div><div> 0.87500000 0.00000000 0.00000000 </div><div>End KPoints</div></div><div><br></div><div><br></div><div><br></div><div><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><span><font color="#888888">Zeina Salman<br>PhD Candidate<br>Microelectronics and Photonics Graduate Program <br>University of Arkansas<br>Fayetteville, AR 72701<br>Office: PHYS 244<br>Email: <a href="mailto:zaldolam@email.uark.edu" target="_blank">zaldolam@email.uark.edu</a><a href="mailto:cxm075@email.uark.edu" target="_blank"></a></font></span></div></div></div></div>
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