[QE-users] Problem with Cholesky

[Paolo Giannozzi]

On Tue, Feb 8, 2022 at 12:19 PM Aritri Roy <aritrits at kgpian.iitkgp.ac.in>
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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-- 
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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