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<p>Dear Abhirup,</p>
<p><br>
</p>
<p><font size="4">> However, I am not sure with the number of atoms (~120 or more) GW-BSE calculations with supercell is actually feasible.
</font><br>
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<p><br>
</p>
<p>Yes, I understand the issue. I do not know if it is feasible. You may try to use e.g. Yambo and see how it goes. Otherwise, since you have already quite a big cell, maybe with k=0 you obtain quite a reasonably converged spectrum (to be checked w.r.t. the
cell size) at the TDDFT level in the adiabatic approximation.</p>
<p><br>
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<p>Regards,</p>
<p>Iurii<br>
</p>
<p><br>
</p>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
Dr. Iurii Timrov<br>
Postdoctoral Researcher<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080"><font size="3" face="'Times New Roman', Times, serif" color="808080">Swiss Federal Institute of Technology Lausanne (EPFL<font color="808080"><font face="'Times New Roman', Times, serif">)</font></font></font><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of Abhirup Patra <abhirupp@sas.upenn.edu><br>
<b>Sent:</b> Tuesday, December 17, 2019 4:47:01 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> Re: [QE-users] k-point algorithm is not tested yet turbo davidson</font>
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<div class="gmail_default" style="font-size:large">Thanks very much, Iurii. I really appreciate your answer and it does make sense to me. With gamma point only it works fine. And, you are right, my system is a solid and I am
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<div class="gmail_default" style="font-size:large">trying to simulate the optical spectrum. However, I am not sure with the number of atoms (~120 or more) GW-BSE calculations with supercell is actually feasible.
<br>
</div>
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">Best,</div>
<div class="gmail_default" style="font-size:large">Abhirup<br>
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<div dir="ltr"><font face="arial, sans-serif" color="#0b5394">-------------------------------------------------------------------------------------------------------------------------------------</font>
<div><font face="arial, sans-serif" color="#0b5394">Abhirup Patra</font></div>
<div><font face="arial, sans-serif" color="#0b5394">Postdoctoral Research Fellow</font></div>
<div><font face="arial, sans-serif" color="#0b5394">Department of Chemistry</font></div>
<div><font face="arial, sans-serif" color="#0b5394">University of Pennsylvania</font></div>
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<div dir="ltr" class="gmail_attr">On Tue, Dec 17, 2019 at 7:50 AM Timrov Iurii <<a href="mailto:iurii.timrov@epfl.ch">iurii.timrov@epfl.ch</a>> wrote:<br>
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<p>Dear Abhirup,</p>
<p><br>
</p>
<p>As you can see from the error message of the turbo_davidson code, the k-points algorithm is not supported. Only Gamma point sampling can be used.</p>
<p><br>
</p>
<p>If I understand correctly, your system is a solid, right? And you want to use a unit cell with a k-points mesh, right? The turbo_davidson cannot be used in this case. You may try to use a supercell with a Gamma point sampling. But be careful when using TDDFT
in the adiabatic approximation for the absorption spectroscopy of solids. I recommend that you check literature on this topic. Maybe you will need to resort to the BSE approach.</p>
<p><br>
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<p>HTH</p>
<p><br>
</p>
<p>Iurii Timrov<br>
</p>
<p><br>
</p>
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<div name="divtagdefaultwrapper"><font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
Dr. Iurii Timrov<br>
Postdoctoral Researcher<br>
<font color="808080"><font face="'Times New Roman', Times, serif"></font></font></font></div>
<font color="808080"></font>
<div name="divtagdefaultwrapper"><font size="3" face="'Times New Roman', Times, serif" color="808080">STI - IMX
<font color="808080"><font face="'Times New Roman', Times, serif">- THEOS</font></font></font><font size="3" face="'Times New Roman', Times, serif" color="808080"> and NCCR - MARVEL<br>
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<div name="divtagdefaultwrapper"><font size="3" face="'Times New Roman', Times, serif" color="808080"><font size="3" face="'Times New Roman', Times, serif" color="808080">Swiss Federal Institute of Technology Lausanne (EPFL<font color="808080"><font face="'Times New Roman', Times, serif">)</font></font></font><br>
</font></div>
<font color="808080"></font>
<div name="divtagdefaultwrapper"><font size="3" face="'Times New Roman', Times, serif" color="808080">CH-1015 Lausanne, Switzerland<br>
+41 21 69 34 881</font></div>
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<div id="gmail-m_-625169129654915766divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> users <<a href="mailto:users-bounces@lists.quantum-espresso.org" target="_blank">users-bounces@lists.quantum-espresso.org</a>>
on behalf of Abhirup Patra <<a href="mailto:abhirupp@sas.upenn.edu" target="_blank">abhirupp@sas.upenn.edu</a>><br>
<b>Sent:</b> Monday, December 16, 2019 6:12:08 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> [QE-users] k-point algorithm is not tested yet turbo davidson</font>
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<div class="gmail_default" style="font-size:large">Hello, <br>
</div>
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">I am trying to use turbo_davidson starting from a SCF calculation using PBE without smearing and spin-polarization. This system is a non-metal with bandgap of 2.6 eV. I gave uniform k-mesh as follows for the
bcc structure with lattice constant of 10.34 angstrom. <br>
</div>
<br>
K_POINTS {crystal_b}<br>
9<br>
0.0 0.0 0.0 0<br>
0.0 -0.5 0.0 0<br>
0.0 -0.5 0.5 0<br>
0.5 -0.5 0.5 0<br>
0.5 -0.5 0.0 0<br>
0.5 0.0 0.0 0<br>
0.0 0.0 0.0 0<br>
0.0 0.0 0.5 0<br>
0.5 0.0 0.5 0
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">&lr_input<br>
prefix = 'pristine_pbe'<br>
outdir = './'<br>
! wfcdir = './'<br>
/<br>
&lr_dav<br>
num_eign = 35,<br>
num_init = 70,<br>
num_basis_max = 200,<br>
start = 0.0d0<br>
finish = 3.5d0<br>
step = 0.001d0<br>
broadening = 0.005d0<br>
/</div>
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">However, I am getting the following error:</div>
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large"> Error in routine lr_readin (1):<br>
k-point algorithm is not tested yet</div>
<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">I am wondering if there is a simple way out to this problem other than explicitly testing different k mesh combinations.
<br>
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<div class="gmail_default" style="font-size:large"><br>
</div>
<div class="gmail_default" style="font-size:large">Best,</div>
<div class="gmail_default" style="font-size:large">Abhirup<br clear="all">
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<div dir="ltr"><font face="arial, sans-serif" color="#0b5394">-------------------------------------------------------------------------------------------------------------------------------------</font>
<div><font face="arial, sans-serif" color="#0b5394">Abhirup Patra</font></div>
<div><font face="arial, sans-serif" color="#0b5394">Postdoctoral Research Fellow</font></div>
<div><font face="arial, sans-serif" color="#0b5394">Department of Chemistry</font></div>
<div><font face="arial, sans-serif" color="#0b5394">University of Pennsylvania</font></div>
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