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<p>Dear Dominik,<br>
<br>
I have run the updated Bi example. The WCC plots are identical to your reference plot. Thankyou greatly for updating the example and attaching your plot as reference.</p>
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<span style="font-size:12.0pt; color:black">Best wishes,<br>
Nathan</span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Dominik Gresch <greschd@gmx.ch><br>
<b>Sent:</b> 28 January 2021 21:17:01<br>
<b>To:</b> Johnson, Nathan; z2pack@lists.phys.ethz.ch<br>
<b>Subject:</b> Re: Output for Bi Example</font>
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<p>Dear Nathan,</p>
<p><br>
</p>
<p>The results for kx=0.5 near 0.8 on the x-axis look a bit suspicious. I can't really identify the problem from the Wannier input file alone though.</p>
<p>In the meantime however, I have updated the Bi example with a pseudopotential that works with newer QE versions:
<a moz-do-not-send="true" href="https://github.com/Z2PackDev/Z2Pack/tree/dev/current/examples/fp/espresso/6.2/Bi">
https://github.com/Z2PackDev/Z2Pack/tree/dev/current/examples/fp/espresso/6.2/Bi</a></p>
<p><br>
</p>
<p>Maybe you can find the difference by studying the example, I have attached the plot produced by the example for reference.</p>
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</p>
<p>Best,</p>
<p>Dominik<br>
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<div class="moz-cite-prefix">On 28.01.21 13:27, Johnson, Nathan wrote:<br>
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<blockquote type="cite" cite="mid:a9ba605d0a054a65bae632d109075058@student.liverpool.ac.uk">
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color:black;mso-fareast-language:EN-GB">Hi Dominik,<o:p></o:p></span></p>
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<span style="font-size:12.0pt;mso-ascii-font-family:Calibri;mso-fareast-font-family:"Times
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Thanks for your reply and insight. </span></p>
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<span style="font-size:12.0pt;mso-ascii-font-family:Calibri;mso-fareast-font-family:"Times
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color:black;mso-fareast-language:EN-GB">I have attached
some new plots for the systems with .win files being the attached bi.win. The Chern and Z2 invariants of each plot are 0. Are these outputs correct?</span></p>
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<span style="font-size: 12pt;">Best wishes,<br>
</span><span style="font-size: 12pt;">Nathan</span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Dominik Gresch
<a class="moz-txt-link-rfc2396E" href="mailto:greschd@gmx.ch"><greschd@gmx.ch></a><br>
<b>Sent:</b> 12 January 2021 22:25:00<br>
<b>To:</b> Johnson, Nathan; <a class="moz-txt-link-abbreviated" href="mailto:z2pack@lists.phys.ethz.ch">
z2pack@lists.phys.ethz.ch</a><br>
<b>Subject:</b> Re: Output for Bi Example</font>
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<p>Dear Nathan,</p>
<p><br>
</p>
<p>I am unsure why the pseudopotential included in the example no longer works; maybe there was a change in the format that is acceptable by QE. Since this error has been reported before, I have
<a href="https://github.com/Z2PackDev/Z2Pack/issues/108" moz-do-not-send="true">created an issue</a> to investigate it.<br>
<br>
In any case, at least for the "<span style="font-size:12.0pt; font-family:"Times New
Roman",serif"><a href="https://www.quantum-espresso.org/upf_files/Bi.pbe-dn-kjpaw_psl.1.0.0.UPF" target="_blank" moz-do-not-send="true"><span style="color:windowtext; text-decoration:none">Bi.pbe-dn-kjpaw_psl.1.0.0.UPF</span></a></span>"
pseudopotential the input files need changing because the "z_valence" of the pseudo is 15 (instead of 5 for the previous pseudopotential). That means that we will have 30 instead of 10 occupied states.</p>
<p><br>
</p>
<p>That means `nbnd` in `bi.nscf.in` needs to be changed to some number larger than 30, let's pick 36 for example (adding a few to make sure all occupied states are converged). In the .win file, we will need to change `num_wann` and `num_bands` to 30, and `exclude_bands`
to `31 - 36`.</p>
<p>These values generally need to be changed when investigating different systems, such that the occupied subspace is considered.</p>
<p><br>
</p>
<p>From the plots, you can also see that the results are incorrect: The WCC should follow a smooth evolution. Abrupt changes in WCC position are generally a sign of trouble. They can happen (mostly when the direct band gap is very low) but it should eventually
converge to a continuous evolution as more "lines" are added in the convergence routine. The evaluation of the topological invariants relies on this continuous evolution, meaning that the results are meaningless if the WCC evolution is discontinuous.</p>
<p><br>
</p>
<p>Hope this helps,<br>
</p>
<p><br>
</p>
<p>Best regards,</p>
<p>Dominik<br>
</p>
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<p><br>
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<div class="moz-cite-prefix">On 11.01.21 14:36, Johnson, Nathan wrote:<br>
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<span style="font-size:12.0pt;
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">I have Z2Pack 2.1.1 set up with first principles code as Quantum Espresso version 6.4.1 with interface to Wannier90 3.1.0. I have run calculations for Z2Pack's Bi example
and would like to see how our output compares.</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">Calculations have been performed for two Bi systems with pseudopotentials <a href="https://www.quantum-espresso.org/upf_files/Bi.pbe-dn-kjpaw_psl.1.0.0.UPF" target="_blank" moz-do-not-send="true"><span style="color:windowtext; text-decoration:none">Bi.pbe-dn-kjpaw_psl.1.0.0.UPF</span></a> and <u>Bi.pbe-d-mt.UPF</u>
using the provided run.py script. These pseudopotentials were used instead of the supplied pseudopotential as the error,</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif"> Error in routine readpp (1):</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif"> file ../input/Bi_MT_PBE.UPF not readable</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">", was returned during an attempted SCF run using the pseudopotential. The values used for converge parameters were the same values as those corresponding to converge parameters
in the _run.py file located in the 'surface' folder of the Z2Pack 2.1.1 distribution. </span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">What ought the output for this example be?</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">I have found a Z2Pack WCC plot corresponding to 'half the k<sub>z</sub>=0 plane of Bismuth' on page 82 of the Topological Matter School Lectures, however, the surfaces of
the example seem to be half the k<sub>x</sub>=0 and k<sub>x</sub>=0.5 planes. With the working assumption that the allotrope of Bi corresponding to the Topological Matter School plot is the same allotrope of Bi as that for which the ionic configuration of
the example corresponds to, I also performed calculations for both Bi systems using ‘surface=lambda s, t: [t, s / 2, 0]’. I am uncertain, however, that the vertical axis of the WCC plots generated by calculations on this surface would correspond to the x-axis
of direct space.</span></p>
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<span style="font-size:12.0pt;
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">I attach the output of aforementioned calculations - please find attached the .win file for both Bi systems and WCC plots.
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">Looking forward to hearing from you,</span></p>
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<span style="font-size:12.0pt;
font-family:"Times New Roman",serif">Best wishes,</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;
line-height:107%; color:black; background:white">Nathan Johnson, PhD student UK</span></p>
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