<div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Here is the input file:</div><div><br></div><div> &control<br> calculation = 'scf'<br> restart_mode='from_scratch',<br>pseudo_dir = './../../../Pseudo',<br>prefix='arsenene',<br>verbosity = 'high'<br>/<br>&system<br> ibrav = 4,<br> nat= 2, ntyp= 1,<br> ibrav= 4,<br> celldm(1) =7.8,<br> celldm(3) =6.103648,<br><br>ecutwfc =30.0,<br>occupations='smearing',<br>smearing='gauss', degauss=0.02,<br>lspinorb=.true<br>noncolin=.true<br>nbnd = 20<br>/<br>&electrons<br>!diagonalization='david'<br>electron_maxstep = 300<br>!mixing_mode = 'plain'<br>mixing_beta = 0.7<br>conv_thr = 1.0d-10<br>/<br>ATOMIC_SPECIES<br>As 74.9216 As.rel-pbe-n-rrkjus_psl.0.2.UPF<br>ATOMIC_POSITIONS crystal<br>As 0.333333333 0.666666666 0.524859275<br>As 0.666666666 0.333333333 0.475140725<br><span style="background-color:rgb(0,255,0)">K_POINTS crystal<br>1<br>0.5 0.0 0.0 1</span></div><div><br></div><div><br></div><div>Note that in the above highlighted portion I am using one of the TRIM points, i.e. M1. Where other TRIM points are M2, M3 and G with coordinates 0.0 0.5 0.0, -0.5 0.0 0.0 and 0.0 0.0 0.0 respectively.</div><div>After SCF (pw.x) calculation, I run the bands,x calculation. The relevant portion of the output is :</div><div><br></div><div> **************************************************************************<br><br> <span style="background-color:rgb(0,255,0)">xk=( -0.50000, 0.28868, 0.00000 )</span><br><br> double point group C_2h (2/m) <br> there are 8 classes and 4 irreducible representations<br> the character table:<br><br> E -E C2 -C2 i -i s_h -s_h <br> <br>G_3+ 1.00 -1.00 0.00 0.00 1.00 -1.00 0.00 0.00<br>G_4+ 1.00 -1.00 0.00 0.00 1.00 -1.00 0.00 0.00<br>G_3- 1.00 -1.00 0.00 0.00 -1.00 1.00 0.00 0.00<br>G_4- 1.00 -1.00 0.00 0.00 -1.00 1.00 0.00 0.00<br><br> imaginary part<br><br> E -E C2 -C2 i -i s_h -s_h <br> <br>G_3+ 0.00 0.00 1.00 -1.00 0.00 0.00 1.00 -1.00<br>G_4+ 0.00 0.00 -1.00 1.00 0.00 0.00 -1.00 1.00<br>G_3- 0.00 0.00 1.00 -1.00 0.00 0.00 -1.00 1.00<br>G_4- 0.00 0.00 -1.00 1.00 0.00 0.00 1.00 -1.00<br><br> the symmetry operations in each class and the name of the first element:<br><br> E 1<br> <br> -E -1<br> <br> C2 2<br> <br> -C2 -2<br> <br> i 3<br> <br> -i -3<br> <br> s_h 4<br> <br> -s_h -4<br> <br><br> Band symmetry, C_2h (2/m) double point group:<br><br> e( 1 - 2) = -14.19192 eV 2 --> G_3- <br> e( 1 - 2) = -14.19192 eV 2 --> G_4- <br> e( 3 - 4) = -12.67503 eV 2 --> G_3+ <br> e( 3 - 4) = -12.67503 eV 2 --> G_4+ <br> e( 5 - 6) = -6.29105 eV 2 --> G_3+ <br> e( 5 - 6) = -6.29105 eV 2 --> G_4+ <br> e( 7 - 8) = -5.79866 eV 2 --> G_3- <br> e( 7 - 8) = -5.79866 eV 2 --> G_4- <br> e( 9 - 10) = -4.65984 eV 2 --> G_3- <br> e( 9 - 10) = -4.65984 eV 2 --> G_4- <br> e( 11 - 12) = -2.39948 eV 2 --> G_3+ <br> e( 11 - 12) = -2.39948 eV 2 --> G_4+ <br> e( 13 - 14) = -0.22470 eV 2 --> G_3- <br> e( 13 - 14) = -0.22470 eV 2 --> G_4- <br> e( 15 - 16) = 0.10174 eV 2 --> G_3+ <br> e( 15 - 16) = 0.10174 eV 2 --> G_4+ <br> e( 17 - 18) = 2.74250 eV 2 --> G_3+ <br> e( 17 - 18) = 2.74250 eV 2 --> G_4+ <br> e( 19 - 20) = 3.59948 eV 2 --> G_3- <br> e( 19 - 20) = 3.59948 eV 2 --> G_4- </div><div><br></div><div>Is highlighted K point in the output file okay?? since I used 0.5 0 0 but it is <span style="background-color:rgb(0,255,0)">xk=( -0.50000, 0.28868, 0.00000 ).</span></div><div>Moreover, I get the same result for M2 and M3 (which should not happen because then Z2 = 0 which contradicts the dedfinitions of TI)</div><div><br></div><div>Please help.<br></div><div><br></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Sep 27, 2018 at 4:19 PM Asad Mahmood <<a href="mailto:amahmood@phys.qau.edu.pk" target="_blank">amahmood@phys.qau.edu.pk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi everyone,</div><div><br></div><div>I am working with 2D materials, applying biaxial strain. At some strain value, the electronic structure exhibits the band diagram similar to that of a Topological Insulator (as I could observe band inversion from partial DOS too). The material I am working with has inversion symmetry which implies that I can find parity eigen values at different bands(then I can find Z2 Topological Invariant using parity eigen values).</div><div>My question is:</div><div><br></div><div>How can we obtain parities (or directly Z2 values, if possible) using Quantum Espresso for a given band diagram?</div><div><br></div><div>Regards,</div><div>Asad Mahmood,</div><div>Physics Department,</div><div>Q.A.U, Islamabad,</div><div>Pakistan<br></div></div>
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