[Pw_forum] Problems with nscf diago with many bands

[Conor Hogan]

Hello again, forget that last message, problem solved:

<      CG style diagonalization
<      ethr =  5.00E-06,  avg # of iterations = 34.7
<      PWSCF        :  3m47.44s CPU time,     3m59.01s wall time

>      Davidson diagonalization with overlap
>      ethr =  5.00E-06,  avg # of iterations = 27.2
>      PWSCF        :  7m41.49s CPU time,     7m47.46s wall time

Wasn't expecting to see CG faster! PW continues to amaze me with its
brutal efficiency :)

cheers
Conor


On Tue, September 30, 2008 11:57 am, Conor Hogan said:
> Dear forum,
> I'm doing a slab calculation, and for reasons I wont explain, I need to
> obtain the nscf KS states for many many unoccupied bands. There are 96
> occupied bands: using the davidson I can diagonalize ok for 500 bands and
> 1000 bands, but if I push it up to 1500 I get problems with (3.2.3):
>      from cdiaghg : error #      2684
>      info =/= 0
> or (4.0):
>      from  pzpotrf  : error #        94
>       problems computing cholesky decomposition
>
> I fear the conjugate gradient will be very slow, so before I try that, any
> suggestions for either approach with so many bands?
>
> I'm using the system compiled pw.x on BCX.
> Cheers,
> Conor
>
>  &system
>       ecutwfc =12.0,
>       nbnd=1500,
>  /
>  &electrons
>     diago_thr_init=5.0e-6,
>     diago_full_acc=.true.
>     electron_maxstep = 70,
>     diagonalization='david'
>     mixing_mode = 'plain'
>     mixing_beta = 0.7
>     conv_thr =  1.0d-8,
>  /
>
>
>
> ----
>
> Dr. Conor Hogan                                --- -----  ---   ---
> Dipartimento di Fisica e CNR-INFM             |      :   |     :
> Universita' di Roma "Tor Vergata"             |--    :    ---  |---
> Tel: +39 06 7259 4121 *NEW*                   |      :       | :
> Fax: +39 06 2023507                            ---   :    ---  :
> http://www.fisica.uniroma2.it/~cmtheo-group/  European Theoretical
>                                               Spectroscopy Facility
>                                               http://www.etsf.eu
>
> Q. What do you call a fish with no eyes?
> A. A fsh.   (Tommy Cooper)
>
> The early bird gets the worm, but the second mouse gets the cheese. - S.
> Wright
>
> If you go through a lot of hammers each month, I don't think it
> necessarily
> means you're a hard worker. It may just mean that you have a lot to learn
> about proper hammer maintenance - J. Handey
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----

Dr. Conor Hogan                                --- -----  ---   ---
Dipartimento di Fisica e CNR-INFM             |      :   |     :
Universita' di Roma "Tor Vergata"             |--    :    ---  |---
Tel: +39 06 7259 4121 *NEW*                   |      :       | :
Fax: +39 06 2023507                            ---   :    ---  :
http://www.fisica.uniroma2.it/~cmtheo-group/  European Theoretical
                                              Spectroscopy Facility
                                              http://www.etsf.eu

Q. What do you call a fish with no eyes?
A. A fsh.   (Tommy Cooper)

The early bird gets the worm, but the second mouse gets the cheese. - S.
Wright

If you go through a lot of hammers each month, I don't think it necessarily
means you're a hard worker. It may just mean that you have a lot to learn
about proper hammer maintenance - J. Handey