About the relationship between the reciprocal and real spaces, you can find in some book of Solid State, authors like Ashcroft or Kittel. In order to select the number of k-points you need to do convergence of the total energy (or your observable) respect the number of k-points...!!! The same criteria to select the optimal value of cut-off energy and perhaps also for the length of the third vector (z direction) because you should consider the periodicity of QE.<br>
<br>Best.<br><br>PhD std. Arles V. Gil Rebaza<br>Instituto de Física de La Plata<br>La Plata-Argentina<br><br><br><div class="gmail_quote">2011/5/9 swapnil chandratre <span dir="ltr"><<a href="mailto:swapnil.chandratre@gmail.com">swapnil.chandratre@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hello,<div><br></div><div><br></div><div>Thank you all for your responses, I was using a software to generate the geometry of ribbon, it gave me the data regarding the <b>unit cell </b>dimensions so I just transfered the data from there. And when I visualized it there, it seemed to be perfect, I am trying to install XCrysden so that I can avoid such issues again.</div>
<div><br></div><div>Arles, can you shed some knowledge on how to go for the k points, as it is 1d,I assume 100 k points may be sufficient to give reasonable idea, I just randomly selected 25 as a starting point, and can anyone suggest any reading material or approach towards defining the cut off energies and K points.</div>
<div><br></div><div>Thank you.</div><div><br><div class="gmail_quote">On Mon, May 9, 2011 at 9:44 AM, Arles V. Gil Rebaza <span dir="ltr"><<a href="mailto:arvifis@gmail.com" target="_blank">arvifis@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Your unit cell vectors are wrong, because many atoms positions are out the unit cell..!! futhermore, why do you put 25 1 1 k-points...?? remember that the reciprocal space is inversely proportional to real space....!!!<br>
<br>Best.<br><br>PhD std. Arles V. Gil Rebaza<br>Instituto de Física de La Plata<br>La Plata-Argentina<div><div></div><div><br><br><div class="gmail_quote">2011/5/9 mousumi uk <span dir="ltr"><<a href="mailto:larikamonu@gmail.com" target="_blank">larikamonu@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Your unit cell is wrong.... visualize your structure in xcrysden and correct the CELL_PARAMETERS.<br><br>
Best regards,<br>Mousumi<br><br><div class="gmail_quote"><div><div></div><div>On Mon, May 9, 2011 at 6:36 AM, swapnil chandratre <span dir="ltr"><<a href="mailto:swapnil.chandratre@gmail.com" target="_blank">swapnil.chandratre@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex"><div><div></div><div>Hi,<div><br></div><div>I have prepared an input file for a porous graphene nanoribbon, can anyone please comment if there are any errors with the file.</div>
<div><br></div><div><div>&control</div><div> calculation = 'relax'</div>
<div> restart_mode = 'from_scratch'</div><div> pseudo_dir = '/home/s/schandratre/Espresso/pseudo'</div><div> outdir = '/home/s/schandratre/Espresso/run'</div><div><br></div><div>
/</div><div> &system</div><div> </div><div> ibrav = 0</div><div>nat=96</div><div>ntyp=2</div><div>ecutwfc=80.0</div><div>ecutrho = 600.0</div><div>occupations = 'smearing'</div><div>degauss=0.02</div><div>
smearing = 'gaussian',</div><div> /</div><div> &electrons</div><div> conv_thr = 1.0d-6,</div><div> mixing_beta=0.3,</div><div> /</div><div>&ions</div><div>ion_dynamics='damp'</div><div>pot_extrapolation='second_order'</div>
<div>wfc_extrapolation='second_order'</div><div>/</div><div><br></div><div>ATOMIC_SPECIES</div><div>C 12.0000 C.pz-rrkjus.UPF</div><div>H 1.00000 H.pz-rrkjus.UPF</div><div><br></div><div>ATOMIC_POSITIONS {angstrom}</div>
<div> C 2.841720 5.953494 5.000000</div><div> C 3.552150 7.183995 5.000000</div><div> C 1.420860 5.953494 5.000000</div><div> C 2.841720 8.414496 5.000000</div><div> C 3.552150 9.644997 5.000000</div>
<div> C 0.710430 7.183995 5.000000</div><div> C 1.420860 8.414496 5.000000</div><div> C 2.841720 10.87550 5.000000</div><div> C 3.552150 12.10600 5.000000</div><div> C 0.710430 9.644997 5.000000</div>
<div> C 1.420860 10.87550 5.000000</div><div> C 2.841720 13.33650 5.000000</div><div> C 3.552150 14.56700 5.000000</div><div> C 0.710430 12.10600 5.000000</div><div> C 1.420860 13.33650 5.000000</div>
<div> C 0.710430 14.56700 5.000000</div><div> H 3.392220 5.000000 5.000000</div><div> H 0.870360 5.000000 5.000000</div><div> H 3.001650 15.52049 5.000000</div><div> H 1.260930 15.52049 5.000000</div>
<div> C 7.104300 5.953494 5.000000</div><div> C 7.814730 7.183995 5.000000</div><div> C 5.683440 5.953494 5.000000</div><div> C 7.104300 8.414496 5.000000</div><div> C 4.973010 7.183995 5.000000</div>
<div> C 5.683440 8.414496 5.000000</div><div> C 7.104300 10.87550 5.000000</div><div> C 7.814730 12.10600 5.000000</div><div> C 4.973010 9.644997 5.000000</div><div> C 5.683440 10.87550 5.000000</div>
<div> C 7.104300 13.33650 5.000000</div><div> C 7.814730 14.56700 5.000000</div><div> C 4.973010 12.10600 5.000000</div><div> C 5.683440 13.33650 5.000000</div><div> C 4.973010 14.56700 5.000000</div>
<div> H 7.654800 5.000000 5.000000</div><div> H 5.132940 5.000000 5.000000</div><div> H 7.264230 15.52049 5.000000</div><div> H 5.523510 15.52049 5.000000</div><div> C 11.36688 5.953494 5.000000</div>
<div> C 12.07731 7.183995 5.000000</div><div> C 9.946020 5.953494 5.000000</div><div> C 11.36688 8.414496 5.000000</div><div> C 12.07731 9.644997 5.000000</div><div> C 9.235590 7.183995 5.000000</div>
<div> C 11.36688 10.87550 5.000000</div><div> C 12.07731 12.10600 5.000000</div><div> C 11.36688 13.33650 5.000000</div><div> C 12.07731 14.56700 5.000000</div><div> C 9.235590 12.10600 5.000000</div>
<div> C 9.946020 13.33650 5.000000</div><div> C 9.235590 14.56700 5.000000</div><div> H 11.91738 5.000000 5.000000</div><div> H 9.395520 5.000000 5.000000</div><div> H 11.52681 15.52049 5.000000</div>
<div> H 9.786090 15.52049 5.000000</div><div> C 15.62946 5.953494 5.000000</div><div> C 16.33989 7.183995 5.000000</div><div> C 14.20860 5.953494 5.000000</div><div> C 15.62946 8.414496 5.000000</div>
<div> C 16.33989 9.644997 5.000000</div><div> C 13.49817 7.183995 5.000000</div><div> C 14.20860 8.414496 5.000000</div><div> C 15.62946 10.87550 5.000000</div><div> C 16.33989 12.10600 5.000000</div>
<div> C 13.49817 9.644997 5.000000</div><div> C 14.20860 10.87550 5.000000</div><div> C 15.62946 13.33650 5.000000</div><div> C 16.33989 14.56700 5.000000</div><div> C 13.49817 12.10600 5.000000</div>
<div> C 14.20860 13.33650 5.000000</div><div> C 13.49817 14.56700 5.000000</div><div> H 16.17996 5.000000 5.000000</div><div> H 13.65810 5.000000 5.000000</div><div> H 15.78939 15.52049 5.000000</div>
<div> H 14.04867 15.52049 5.000000</div><div> C 19.89204 5.953494 5.000000</div><div> C 20.60247 7.183995 5.000000</div><div> C 18.47118 5.953494 5.000000</div><div> C 19.89204 8.414496 5.000000</div>
<div> C 20.60247 9.644997 5.000000</div><div> C 17.76075 7.183995 5.000000</div><div> C 18.47118 8.414496 5.000000</div><div> C 19.89204 10.87550 5.000000</div><div> C 20.60247 12.10600 5.000000</div>
<div> C 17.76075 9.644997 5.000000</div><div> C 18.47118 10.87550 5.000000</div><div> C 19.89204 13.33650 5.000000</div><div> C 20.60247 14.56700 5.000000</div><div> C 17.76075 12.10600 5.000000</div>
<div> C 18.47118 13.33650 5.000000</div><div> C 17.76075 14.56700 5.000000</div><div> H 20.44254 5.000000 5.000000</div><div> H 17.92068 5.000000 5.000000</div><div> H 20.05197 15.52049 5.000000</div>
<div> H 18.31125 15.52049 5.000000</div><div><br></div><div>CELL_PARAMETERS</div><div>19.200000 0.000000 0.000000 </div><div>0.0000000 21.90350 0.000000</div><div>0.0000000 0.000000 10.00000</div><div><br></div><div>
K_POINTS {automatic} </div><div> 25 1 1 0 0 0</div><div><br></div><br>-- <br>Regards,<br>Swapnil Chandratre<br>Graduate Student<br>Dept. of Mechanical Engineering,<br>University of Houston,<br>Houston, TX<br>(M)-<a href="tel:713-294-9546" value="+17132949546" target="_blank">713-294-9546</a><br>
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<br></blockquote></div><br><br clear="all"><br></div></div>-- <br><font color="#888888">###---------> Arles V. <---------###<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Regards,<br>Swapnil Chandratre<br>Graduate Student<br>Dept. of Mechanical Engineering,<br>University of Houston,<br>Houston, TX<br>(M)-713-294-9546<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>###---------> Arles V. <---------###<br>