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<p>Dear Gabriele,</p>
<p><br>
</p>
<p><font size="2"><span style="font-size:10pt">> Things that I have tried (with no joy, and, I must admit, without knowing very well what I was doing):</span></font><br>
</p>
<p><br>
</p>
<p>That's the main problem! You should start exactly from this point. You need to understand every step you do, otherwise what is the point?</p>
<p><br>
</p>
<p>I would recommend to go through the tutorial about TDDFPT:</p>
<p><a href="http://indico.ictp.it/event/7921/session/325/contribution/1280/material/0/0.pdf" class="x_OWAAutoLink" id="LPlnk336079">http://indico.ictp.it/event/7921/session/325/contribution/1280/material/0/0.pdf</a></p>
<p><br>
</p>
<p>What is your input for PW calculation? In the links that you provided there is no one pointing to the PW input. But from the PW output it seems that you are using the VdW correction - do you really need it? For an isolated molecule there is no need in the
VdW correction. So maybe it would be useful also to go through tutorials on basic PW calculations:</p>
<p><a href="http://indico.ictp.it/event/7921/other-view?view=ictptimetable" class="x_OWAAutoLink" id="LPlnk957535">http://indico.ictp.it/event/7921/other-view?view=ictptimetable</a></p>
<p><a href="http://qe2019.ijs.si/program.html" class="x_OWAAutoLink" id="LPlnk988733">http://qe2019.ijs.si/program.html</a></p>
<p><br>
</p>
<p>Greetings,</p>
<p>Iurii<br>
</p>
<p><br>
</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of balducci@units.it <balducci@units.it><br>
<b>Sent:</b> Friday, June 26, 2020 4:04:26 PM<br>
<b>To:</b> users@lists.quantum-espresso.org<br>
<b>Subject:</b> [QE-users] help with turbo-davidson not converging</font>
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<font size="2"><span style="font-size:10pt;">
<div class="PlainText">hello<br>
<br>
I'm having convergence problems with a turbo-davidson calculation on<br>
an isolated (neutral) molecule of a Ru complex:<br>
<br>
<a href="http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/XEDFAQ_1.png">http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/XEDFAQ_1.png</a><br>
<br>
I have limited experience with this kind of calcs, but some time ago I<br>
did similar calcs on another molecule of the same type without any<br>
apparent problem (see also below).<br>
<br>
So far my protocol is:<br>
=> geometry relaxation of the isolated molecule (cubic cell (a=21.50<br>
ang) with a minimum inter-image distance of 10.1 ang, gamma<br>
point)<br>
=> scf calculation with nbnd=120 (there are 96 occupied bands)<br>
<a href="http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/scf.in.txt">
http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/scf.in.txt</a><br>
=> turbo-davidson run:<br>
<a href="http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/davidson.in.txt">
http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/davidson.in.txt</a><br>
<br>
----8<----<br>
&lr_input<br>
outdir='./tmp',<br>
restart=.false.<br>
/<br>
&lr_dav<br>
p_nbnd_occ=10<br>
p_nbnd_virt=10<br>
num_init=60<br>
num_eign=25<br>
num_basis_max=200<br>
residue_conv_thr=1.0E-4<br>
start=0.18866813 ! 483 nm<br>
finish=0.23792873 ! 383 nm<br>
step=0.001<br>
reference=0.21021155 ! 433.5 nm<br>
broadening=0.005<br>
poor_of_ram=.true.<br>
poor_of_ram2=.true.<br>
lplot_drho=.true.<br>
/<br>
----8<----<br>
<br>
As said, the turbo-davidson calculation doesn't seem to be going<br>
anywhere; here is a typical pattern of the "Largest residue" figure vs<br>
n. of iterations:<br>
<br>
<a href="http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/convergence.png">http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/convergence.png</a><br>
<br>
and here is an output:<br>
<br>
<a href="http://www.dsch.univ.trieste.it/~balducci/tmp/turbo-davidson-problem/davidson.out.txt">http://www.dsch.univ.trieste.it/~balducci/tmp/turbo-davidson-problem/davidson.out.txt</a><br>
<br>
Things that I have tried (with no joy, and, I must admit, without<br>
knowing very well what I was doing):<br>
=> increase num_init<br>
=> decrease num_eign<br>
=> decrease the energy range (start,finish)<br>
=> increase num_basis_max<br>
=> switch vdW-DF off in the scf run<br>
=> increase p_nbnd_occ and p_nbnd_virt<br>
<br>
The only way I could get a converged result so far has been to request<br>
a single eigenvalue (num_eign=1): however, I guess this is simply<br>
extreme tweaking of the calculation: even in this conditions, it took<br>
some 22 iterations to converge, which seems too much to me.<br>
<br>
I have tried to reproduce my previous calc (the one which worked<br>
smoothly) since qe version at the time was different (I'm presently<br>
using qe-6.5); the molecule was this (ionic species, charge +2):<br>
<br>
<a href="http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/fbt1805_1.png">http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/fbt1805_1.png</a><br>
<br>
With the following input:<br>
<br>
<br>
----8<----<br>
&lr_input<br>
outdir='./tmp',<br>
restart=.false.<br>
/<br>
&lr_dav<br>
p_nbnd_occ=10<br>
p_nbnd_virt=10<br>
num_init=60<br>
num_eign=25<br>
num_basis_max=200<br>
residue_conv_thr=1.0E-4<br>
start=0.15<br>
finish=0.185<br>
step=0.001<br>
broadening=0.005<br>
reference=0.1675<br>
poor_of_ram=.true.<br>
poor_of_ram2=.true.<br>
lplot_drho=.true.<br>
/<br>
---->8----<br>
<br>
the calculation converges straightforwardly with qe-6.5:<br>
<br>
----8<----<br>
Largest residue: 0.051299398950<br>
Largest residue: 0.014049254805<br>
Largest residue: 0.005898374852<br>
Largest residue: 0.002998212328<br>
Largest residue: 0.003119825980<br>
Largest residue: 0.001028311667<br>
Largest residue: 0.000741910032<br>
Largest residue: 0.000399386757<br>
Largest residue: 0.000545167736<br>
Largest residue: 0.000146498010<br>
Largest residue: 0.000098106072<br>
---->8----<br>
<br>
I'm out of ideas and hoping that someone on the list can give me a<br>
clue (apologies: I realize that the statement of the problem is rather<br>
vague, but I don't know how to be more precise than this)<br>
<br>
Needless to say, I will be happy to provide any further information<br>
which might be useful<br>
<br>
thanks a lot in advance for any hint/suggestion<br>
<br>
ciao<br>
-gabriele<br>
<br>
<br>
-- <br>
Gabriele Balducci - Dipartimento di Scienze Chimiche e Farmaceutiche - Via<br>
L. Giorgieri 1 I-34127 TRIESTE tel: I-040-5583957 fax: I-040-5583903 e-mail:<br>
balducci@units.it Please, if possible, don't send me MS Word or PowerPoint<br>
attachments Why? See: <a href="http://www.gnu.org/philosophy/no-word-attachments.html">
http://www.gnu.org/philosophy/no-word-attachments.html</a><br>
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