<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: times new roman,new york,times,serif; font-size: 12pt; color: #000000'><font face="arial,helvetica,sans-serif">Hello everbody,<br><br><span id="selection_url_f"></span><br>I am trying to simulate some achiral <b><font color="#ff0000">(n ,0) [n= 5, 8, 10]</font></b> zigzag carbon nanotubes in pwscf.<br><br>The following input file is for (8,0):<br><br>&control<br> calculation = 'scf'<br> restart_mode = 'from_scratch'<br> title = 'cnt'<br> verbosity = 'high'<br> pseudo_dir = '',<br> outdir='',<br> prefix='cnt',<br> tprnfor=.true.,<br> tstress=.true.<br><br>/<br><br>&system<br> ibrav= 0<br> celldm(1) = 8.104120169, <br> nat = 32,<br> ntyp = 1,<br> ecutwfc = 60.0,<br> occupations = 'fixed', <br> <br>/<br>&electrons<br> mixing_beta = 0.2<br> conv_thr = 1.0d-9<br>/<br>CELL_PARAMETERS (alat= 4.64872593)<br> 1.00 0.00 0.00<br> 0.00 8.00 0.00<br> 0.00 0.00 8.00<br>ATOMIC_SPECIES<br>C 12.0107 C.oncvpsp.upf<br>ATOMIC_POSITIONS {angstrom}<br>C 2.856428508022 3.209468929586 0.000000203<br>C 3.576345516550 2.965158124213 -1.228208929314<br>C 0.7121704998315 1.228210398531 2.965162731946<br>C 1.432087508359 2.269433979920 2.269433692888<br>C 2.856428508022 -2.269437387634 2.269437100602<br>C 3.576345516550 -1.228208554289 2.965158279554<br>C 0.7121704998315 -2.965162576605 -1.228210773556<br>C 1.432087508359 -3.209464110352 0.000000203<br>C 2.856428508022 0.000000203 -3.209468929586<br>C 3.576345516550 -1.228208929314 -2.965158124213<br>C 0.7121704998315 2.965162731946 -1.228210398531<br>C 1.432087508359 2.269433692888 -2.269433979920<br>C 2.856428508022 2.269437100602 2.269437387634<br>C 3.576345516550 2.965158279554 1.228208554289<br>C 0.7121704998315 -1.228210773556 2.965162576605<br>C 1.432087508359 0.000000203 3.209464110352<br>C 2.856428508022 -3.209468929586 -0.000000203<br>C 3.576345516550 -2.965158124213 1.228208929314<br>C 0.7121704998315 -1.228210398531 -2.965162731946<br>C 1.432087508359 -2.269433979920 -2.269433692888<br>C 2.856428508022 2.269437387634 -2.269437100602<br>C 3.576345516550 1.228208554289 -2.965158279554<br>C 0.7121704998315 2.965162576605 1.228210773556<br>C 1.432087508359 3.209464110352 -0.000000203<br>C 2.856428508022 -0.000000203 3.209468929586<br>C 3.576345516550 1.228208929314 2.965158124213<br>C 0.7121704998315 -2.965162731946 1.228210398531<br>C 1.432087508359 -2.269433692888 2.269433979920<br>C 2.856428508022 -2.269437100602 -2.269437387634<br>C 3.576345516550 -2.965158279554 -1.228208554289<br>C 0.7121704998315 1.228210773556 -2.965162576605<br>C 1.432087508359 -0.000000203 -3.209464110352<br>K_POINTS {automatic}<br>8 1 1 0 0 0</font><pre><font face="arial,helvetica,sans-serif"><br> <br>The point group symmetry of any achiral <b><font color="#ff0000">(n, 0)</font></b> CNT is <font color="#ff0000">always <u><b> D2nh</b></u></font>, but in the output of my calculations for the three nanotubes </font><font face="arial,helvetica,sans-serif"><font face="arial,helvetica,sans-serif"><b><font color="#ff0000"> [n= 5, 8, 10]</font></b></font>, the symmetry is <font color="#3333ff"><u><b>D4h</b></u></font> regardless of <font color="#ff0000"><b>n</b> </font>value.<br>
I want to know if there is a way to get the right symmetry?
<br><br>Best,<br><br>K<br></font></pre><font face="arial,helvetica,sans-serif"><br><br></font><br></div></body></html>