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<p>Dear Jonathan Backman,</p>
<p>I suggest you to try and set diago_david_ndim = 2 instead of the
default value of diago_david_ndim = 4 if you are using Davidson
diagonalization - it helped me to resolve a similar issue in the
past. The other thing that helped me was changing a pseudo
potenial to a much hard norm-conserving pseudo that contained more
semi-core states, however, for performance reason I edned up using
diago_david_ndim =2 option.</p>
<p>Best regards,<br>
</p>
<div class="moz-cite-prefix">On 19/06/2019 12:47, Jonathan Backman
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:4b7fa96d-eb37-e9da-1a1f-0a01dcb2fb19@iis.ee.ethz.ch">Dear
Quantum Espresso community,
<br>
<br>
I am trying to perform a relax calculation on two different
Ni-MoS2 contacts. One top contact (Ni over single layer MoS2) and
one edge contact (MoS2 connected to the side of Ni), see attached
input file. In both cases I get the error "problems computing
cholesky". It has previously been suggested that this can happen
in the case of "bad" atom positions, but I do not think this is
the case for me, especially since it occurs in both my contacts.
The problem also remains when changing the pseudo potentials.
<br>
<br>
It has also been suggested that the error can be caused by a
parallelization issue. For the edge contact I am running on 792
processor cores (distributed over 33 nodes) divided over 11 pools
(since I have 11 kpoints) with 72 processors per pool. With
current ecutwfc the FFT dimensions are ( 360, 384, 72). To my
understanding should give a effective parallelization, sine number
of processors/pool is smaller or equal to FFR_3 and is a divisor
of it. I have also tried with 264 processors, 24 processors/pool,
but the problem still remains.
<br>
<br>
The calculation is able to perform 2-3 bfgs steps before showing
the error at the beginning of the next scf cycle. If I then take
the last atom positions and perform a new relaxation calculation
it can once again go through 2-3 bfgs steps before error. Using
this method I can continue restarting it, but it is not very
effective. If I instead restart the calculation using the last
saved charge density it shows the error immediately in the first
scf iteration.
<br>
<br>
I would be happy for any suggestions on how to solve this problem.
<br>
Please ask if you want more information.
<br>
<br>
<br>
Best regards,
<br>
Jonathan Backman, PhD student
<br>
Nano-TCAD Group, ETHZ Switzerland
<br>
<a class="moz-txt-link-abbreviated" href="mailto:jbackman@iis.ee.ethz.ch">jbackman@iis.ee.ethz.ch</a>
<br>
<br>
<br>
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</blockquote>
<pre class="moz-signature" cols="72">--
Oleksandr Motornyi
PhD
Laboratoire de Solides Irradies
Ecole Polytechnique (Palaiseau, France)</pre>
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