[Pw_forum] diago_david_ndim

[Paolo Giannozzi]

On Sat, Jan 7, 2017 at 9:50 AM, jqli14 at fudan.edu.cn <jqli14 at fudan.edu.cn>
wrote:


>          In the manual, I found increasing the diago_david_ndim can lead
> to a faster calculation. Can I obtain a very high speed-up by endlessly increasing
> the value of diago_david_ndim  as long as the memory of my machine is
> enough
>

No. The manual is not very accurate, but it doesn't say that. My advice is
quite the opposite: set diago_david_ndim to the minimum (2). What is lost
in terms of H\psi computation is typically compensated by the reduced
dimension on matrices to be diagonalized

Paolo

>
>
> Best regards!
> Jiqiang Li
> Fudan University, China
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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