Re: [QE-users] Problem with Cholesky

[Kazume NISHIDATE]

Dear Aritri

As far as I know, it suppress the parallel operation in the diagonalization.

敬具　西館
best regards

nisid...@iwate-u.ac.jp
kazume.nishid...@gmail.com
2022年2月8日 20:19 +0900、Aritri Roy  のメール:
> HI,
> While running some NEB calculations I faced a problem with computing 
> Cholesky. But adding "-ndiag 1" to the command line solved that problem. But 
> how does this command solve this problem? I would appreciate any insight you 
> can provide.
> Regards,
> Aritri Roy
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Re: [QE-users] Problem with Cholesky

[Paolo Giannozzi]

On Tue, Feb 8, 2022 at 12:19 PM Aritri Roy 
wrote:

While running some NEB calculations I faced a problem with computing
> Cholesky. But adding "-ndiag 1" to the command line solved that problem.
> But how does this command solve this problem?
>

-ndiag 1 => "use serial (LAPACK) subspace diagonalization in iterative
diagonalization"
Otherwise, parallel diagonalization on distributed matrices (ScaLAPACK) is
used. The latter should be perfectly equivalent to the former, and
typically it is, but there can be small numerical differences that in some
unfortunate cases may lead to failure of iterative diagonalization

Paolo

Aritri Roy
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> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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