Dear Jonathan Backman,
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.
Best regards,
On 19/06/2019 12:47, Jonathan Backman wrote:
Dear Quantum Espresso community,
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.
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.
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.
I would be happy for any suggestions on how to solve this problem.
Please ask if you want more information.
Best regards,
Jonathan Backman, PhD student
Nano-TCAD Group, ETHZ Switzerland
[email protected]
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--
Oleksandr Motornyi
PhD
Laboratoire de Solides Irradies
Ecole Polytechnique (Palaiseau, France)
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