[DFTB-Plus-User] Spase matrices and eigenvalue problem

Zbigniew Romanowski romz at wp.pl
Wed May 21 17:03:06 CEST 2008

Dear Dr. Bálint,

Thank you for your fast response concerning the CPU and memory usage.

In one of the previous message 
you wrote:

"Please note, that for big systems DFTB+ spends about 90% of its
execution time in the LAPACK diagonalisation routine. Therefore, you
should make sure, that you're linking the code with an OpenMP capable
BLAS/LAPACK library (e.g. MKL)."

Concerning this statement I have two questions:

1. Is it possible to implement sparse matrices to store H and S matrices 
in current version of DFTB+?

2. Is it of great worth to implement iterative algorithms for solving 
eigenvalue problem? I mean, does it save time  applying ARPACK library 
for sparse matrices instead of LAPACK for full matrices?

Could you please provide the answers for these two questions.

Best regards,
Zbigniew Romanowski


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