[gpaw-users] Changes in the new PAW setups bundle of 26/10 ("gpaw-setups-0.9.9672")

[Ask Hjorth Larsen]

Does anyone have any logfiles demonstrating any of this?

2012/11/23 Marcin Dulak <Marcin.Dulak at fysik.dtu.dk>:
> On 11/23/12 16:01, Ask Hjorth Larsen wrote:
>>
>> Hi
>>
>> 2012/11/23 Marcin Dulak <Marcin.Dulak at fysik.dtu.dk>:
>>>
>>> Hi,
>>>
>>>
>>> On 11/23/12 15:03, Ask Hjorth Larsen wrote:
>>>>
>>>> Hi
>>>>
>>>> 2012/11/23 Marcin Dulak <Marcin.Dulak at fysik.dtu.dk>:
>>>> (...)
>>>>>
>>>>> A negative outcome from the way new setups are generated is that most
>>>>> of
>>>>> them require now eigensolver='cg' or 'dav' to achieve convergence.
>>>>> The new Oxygen setup is also a bit harder, so requires finer grid.
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Marcin
>>>>
>>>> This last part is rather unfortunate because cg and dav, compared to
>>>> rmm-diis, reduce the performance of GPAW by a large factor for systems
>>>> of non-trivial size.  Furthermore those solvers don't support band
>>>> parallelization AFAIK.  What can be done about this?
>>>
>>> i remember Jens Jørgen and your comments about that (old Ti setup case),
>>> can you remind what was your conclusion?
>>> The convergence problems seem to be related to the presence of semicore
>>> p-states:
>>>
>>> https://listserv.fysik.dtu.dk/pipermail/gpaw-developers/2012-September/003190.html
>>
>> I don't think anything was concluded other than that it was nasty.
>>
>> I'm not sure that I have ever seen something that could not be fixed
>> with rmm-diis by having a better initialization or adding more states.
>>
>> Presumably you have some calculations from which it is clear that
>> neither of these helps.  But it'll be a major blow if cg is needed as
>> a default.  I think it's well below half the performance of rmm-diis
>> even when band parallelization is not needed.  So something should be
>> figured out. (Small molecules would of course be the exception because
>> time is spent on XC/Poisson.)
>
> in fact the link above shows
> that starting with cg and switching to rmm (like vasp does) does not help
> for those setups
> (see Mixer() initial cg iter:10 on
> https://wiki.fysik.dtu.dk/gpaw/documentation/convergence/scf_conv_eval.html#deltacodesdft),
> but this has been done with "standard" rmm. I know Jussi is working
> on https://wiki.fysik.dtu.dk/gpaw/devel/projects/rmmdiis.html
> I have also tried to change the energies of the p-projectors (gpaw-setup
> --extra-projectors),
> they have some effect, but still no convergence possible with rmm.
> It seems also that no mixers can help, after testing multitude of different
> ones (including Jussi's FFTMixers).
>
> Marcin
>
>>
>> Regards
>> Ask
>>
>>
>
>
> --
> ***********************************
>  Marcin Dulak
> Technical University of Denmark
> Department of Physics
> Building 307, Room 229
> DK-2800 Kongens Lyngby
> Denmark
> Tel.: (+45) 4525 3157
> Fax.: (+45) 4593 2399
> email: Marcin.Dulak at fysik.dtu.dk
>
> ***********************************
>