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Hello QE Community,
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<div>I have calculated the electronic band structure (without spin orbit coupling) of a 2D organometallic topological insulator: triphenyl-Pb,</div>
<div>reproducing the plot from this paper: Wang, Z., Liu, Z. & Liu, F. Organic topological insulators in organometallic lattices.</div>
<div>Nat Commun 4, 1471 (2013). https://doi.org/10.1038/ncomms2451. I obtain very good agreement.</div>
<div><br>
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<div>However, I find that for my calculation there is a small mismatch between the Fermi energy and the position of the dirac point at K.
</div>
<div>The mismatch is approximately 0.006 eV with the Fermi energy higher.</div>
<div>I thought this mismatch could be a consequence of the metallic smearing used in the calculation.
</div>
<div>The reported contribution to the total energy from the smearing is -TS = -0.00570874 Ry = -0.07767136 eV.</div>
<div>I have used 0.3 eV marzari-vanderbilt smearing in the calculations.</div>
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<div>Is this reasoning correct? What other contributions can cause the mismatch?</div>
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<div><span style="margin:0px;background-color:rgb(255, 255, 255)">Thanks,</span>
<div style="margin:0px;background-color:rgb(255, 255, 255)">Steven Best</div>
<div style="margin:0px;background-color:rgb(255, 255, 255)">PhD Student, </div>
</div>
<div><span style="margin:0px;background-color:rgb(255, 255, 255)">School of Chemistry and Physics, </span><span style="background-color:rgb(255, 255, 255);display:inline !important">Queensland University of Technology, Brisbane, Australia</span><br>
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<div>Below are my input files (QE version 6.3):</div>
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</div>
<div>
<div>###########################################################################################################</div>
<div><br>
</div>
<div># pw.x scf calculation</div>
<div><br>
</div>
<div>&CONTROL</div>
<div> calculation = 'scf',</div>
<div> max_seconds = 72000,</div>
<div> verbosity = 'high',</div>
<div> restart_mode = 'from_scratch',</div>
<div> wf_collect = .T.,</div>
<div> nstep = 200,</div>
<div> tstress = .true.,</div>
<div> tprnfor = .true.,</div>
<div> outdir = './',</div>
<div> prefix = 'SCF_triphenyl_Pb_OM_inf_2D_sheet_NONplanar_0.3eV_t304a',</div>
<div> etot_conv_thr = 1.0d-6,</div>
<div> forc_conv_thr = 1.0d-5,</div>
<div> pseudo_dir = './pseudo'</div>
<div>/</div>
<div>&SYSTEM</div>
<div> ibrav = 12, </div>
<div> A = 12.305661, B = 12.305661, C = 20.0, cosAB = 0.5,</div>
<div> nat = 32, ntyp = 3, ! C=18, H=12, Pb=2</div>
<div> ecutwfc = 60.0, ecutrho = 480.0,</div>
<div> occupations = 'smearing', smearing = 'marzari-vanderbilt', degauss = 0.02205,</div>
<div>/</div>
<div>&ELECTRONS</div>
<div> electron_maxstep = 100,</div>
<div> conv_thr = 1.0d-8,</div>
<div> mixing_mode = 'plain',</div>
<div> mixing_beta = 0.4, mixing_ndim = 8,</div>
<div> diagonalization = 'david'</div>
<div>/</div>
<div>&IONS</div>
<div> ion_dynamics = 'bfgs'</div>
<div>/ </div>
<div>ATOMIC_SPECIES</div>
<div> Pb 207.2 Pb.pbe-dn-kjpaw_psl.0.2.2.UPF</div>
<div> H 1.008 H.pbe-kjpaw_psl.1.0.0.UPF </div>
<div> C 12.011 C.pbe-n-kjpaw_psl.1.0.0.UPF</div>
<div>ATOMIC_POSITIONS (angstrom)</div>
<div> C 1.887951458 1.089922558 9.614560235 </div>
<div> C 1.897161739 2.478716980 9.795131247</div>
<div> C 3.058056895 3.149174969 10.201826686</div>
<div> C 3.094519107 0.403062014 9.798882538</div>
<div> C 4.255445582 1.073514486 10.205501492</div>
<div> C 4.264620685 2.462307471 10.386022641</div>
<div> C 4.954605459 6.434598051 10.203602904</div>
<div> C 4.954765288 7.775193715 9.796929960</div>
<div> C 6.152653343 5.732466782 10.385695674</div>
<div> C 6.152988872 8.476869452 9.614145680</div>
<div> C 7.351027374 7.774685777 9.796148892</div>
<div> C 7.350891338 6.434112052 10.202892391</div>
<div> C 8.040607478 2.462414124 10.385502375</div>
<div> C 8.049072424 1.074051311 10.201623729</div>
<div> C 9.210124709 0.403787071 9.795016930</div>
<div> C 9.247909382 3.148856515 10.204584582</div>
<div> C 10.408959312 2.478560082 9.798036472</div>
<div> C 10.417476033 1.090183030 9.614153988</div>
<div> H 0.998237207 3.074868116 9.635193425</div>
<div> H 2.991811789 4.226209592 10.358631992</div>
<div> H 3.160769651 -0.673988810 9.642207163</div>
<div> H 3.988739061 5.954004099 10.362184021</div>
<div> H 3.989028106 8.256228576 9.638913669</div>
<div> H 5.154406664 0.477394068 10.365382031</div>
<div> H 7.149446547 0.478191613 10.358631345</div>
<div> H 8.316631087 5.953081922 10.360913089</div>
<div> H 8.316906000 8.255223371 9.637391566</div>
<div> H 9.143302088 -0.672828642 9.635510075</div>
<div> H 9.314642621 4.225484042 10.364079361</div>
<div> H 11.308571967 3.074480176 9.641154739</div>
<div> Pb 0.000000000 0.000000000 8.851674686</div>
<div> Pb 6.152648942 3.552431083 11.147874419</div>
<div>K_POINTS (automatic)</div>
<div> 15 15 1 0 0 0</div>
<div><br>
</div>
<div>###########################################################################################################</div>
<div><br>
</div>
<div># pw.x bands calculation</div>
<div><br>
</div>
<div>&CONTROL</div>
<div> calculation = 'bands',</div>
<div> max_seconds = 108000,</div>
<div> verbosity = 'high',</div>
<div> restart_mode = 'from_scratch',</div>
<div> wf_collect = .T.,</div>
<div> nstep = 200,</div>
<div> tstress = .true.,</div>
<div> tprnfor = .true.,</div>
<div> outdir = './',</div>
<div> prefix = 'SCF_triphenyl_Pb_OM_inf_2D_sheet_NONplanar_0.3eV_t304a',</div>
<div> etot_conv_thr = 1.0d-6,</div>
<div> forc_conv_thr = 1.0d-5,</div>
<div> pseudo_dir = './pseudo'</div>
<div>/</div>
<div>&SYSTEM</div>
<div> ibrav = 12, </div>
<div> A = 12.305661, B = 12.305661, C = 20.0, cosAB = 0.5,</div>
<div> nat = 32, ntyp = 3, ! C=18, H=12, Pb=2</div>
<div> ecutwfc = 60.0, ecutrho = 480.0,</div>
<div> occupations = 'smearing', smearing = 'marzari-vanderbilt', degauss = 0.02205,</div>
<div>/</div>
<div>&ELECTRONS</div>
<div> electron_maxstep = 100,</div>
<div> conv_thr = 1.0d-8,</div>
<div> mixing_mode = 'plain',</div>
<div> mixing_beta = 0.4, mixing_ndim = 8,</div>
<div> diagonalization = 'david'</div>
<div>/</div>
<div>&IONS</div>
<div> ion_dynamics = 'bfgs'</div>
<div>/ </div>
<div>ATOMIC_SPECIES</div>
<div> Pb 207.2 Pb.pbe-dn-kjpaw_psl.0.2.2.UPF</div>
<div> H 1.008 H.pbe-kjpaw_psl.1.0.0.UPF </div>
<div> C 12.011 C.pbe-n-kjpaw_psl.1.0.0.UPF</div>
<div>ATOMIC_POSITIONS (angstrom)</div>
<div> C 1.887951458 1.089922558 9.614560235 </div>
<div> C 1.897161739 2.478716980 9.795131247</div>
<div> C 3.058056895 3.149174969 10.201826686</div>
<div> C 3.094519107 0.403062014 9.798882538</div>
<div> C 4.255445582 1.073514486 10.205501492</div>
<div> C 4.264620685 2.462307471 10.386022641</div>
<div> C 4.954605459 6.434598051 10.203602904</div>
<div> C 4.954765288 7.775193715 9.796929960</div>
<div> C 6.152653343 5.732466782 10.385695674</div>
<div> C 6.152988872 8.476869452 9.614145680</div>
<div> C 7.351027374 7.774685777 9.796148892</div>
<div> C 7.350891338 6.434112052 10.202892391</div>
<div> C 8.040607478 2.462414124 10.385502375</div>
<div> C 8.049072424 1.074051311 10.201623729</div>
<div> C 9.210124709 0.403787071 9.795016930</div>
<div> C 9.247909382 3.148856515 10.204584582</div>
<div> C 10.408959312 2.478560082 9.798036472</div>
<div> C 10.417476033 1.090183030 9.614153988</div>
<div> H 0.998237207 3.074868116 9.635193425</div>
<div> H 2.991811789 4.226209592 10.358631992</div>
<div> H 3.160769651 -0.673988810 9.642207163</div>
<div> H 3.988739061 5.954004099 10.362184021</div>
<div> H 3.989028106 8.256228576 9.638913669</div>
<div> H 5.154406664 0.477394068 10.365382031</div>
<div> H 7.149446547 0.478191613 10.358631345</div>
<div> H 8.316631087 5.953081922 10.360913089</div>
<div> H 8.316906000 8.255223371 9.637391566</div>
<div> H 9.143302088 -0.672828642 9.635510075</div>
<div> H 9.314642621 4.225484042 10.364079361</div>
<div> H 11.308571967 3.074480176 9.641154739</div>
<div> Pb 0.000000000 0.000000000 8.851674686</div>
<div> Pb 6.152648942 3.552431083 11.147874419</div>
<div>K_POINTS (crystal_b)</div>
<div> 4</div>
<div> 0.0 0.0 0.0 30 ! Gamma</div>
<div> 0.666666667 0.333333333 0.0 30 ! K</div>
<div> 0.5 0.5 0.0 30 ! M</div>
<div> 0.0 0.0 0.0 30 ! Gamma</div>
<div><br>
</div>
<div>###########################################################################################################</div>
<div><br>
</div>
<div># post-processing bands.x</div>
<div><br>
</div>
<div>&bands</div>
<div>outdir = './'</div>
<div>prefix = 'SCF_triphenyl_Pb_OM_inf_2D_sheet_NONplanar_0.3eV_t304a',</div>
<div>filband = 't304c_triphenyl_Pb_OM_inf_2D_sheet_NONp_0.3eV_kpath1.bands.dat',</div>
<div>lsym = .true.</div>
<div>/</div>
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###########################################################################################################<br>
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