[ase-users] how to avoid calculator reset when generating a SumCalculator

[Gaël Donval]

Dear Rochus,

Thanks a lot for the report!

I have opened an issue describing the problem
(https://gitlab.com/ase/ase/-/issues/884). If it's not solved by then I'll write
a fix at some point. 

Regards,
Gaël


> 
> dear ase experts,
> 
> after a bit of fiddling i found a solution for my problem which was
> discussed in a number of emails before. i dare calling it an issue of
> ase, but it might be that this is an intended behavior ... in any case
> the fix is simple and straight forward.
> 
> Note:
> i use the current dftd4 version from conda-forge. it contains "just" a
> regular ase calculator interface. thus, the solution using the older
> interface with D4_model does not work for me.
> 
> Problem:
> I want to restart a GPaw calculation that took a long time to converge
> and pack it into a SumCalculator with DFTD4 and optimize the system. My
> problem was, that the GPaw calculator was triggered to discard the
> wavefunctions and initialize from the LCAO guess again, when wrapping it
> into the SumCalculator like this:
> 
>    dft = GPAW('restart.gpw')
>    system = dft.get_atoms()
>    d4 = DFTD4(method='pbe')
>    sumcalc = SumCalculator([dft, d4], atoms=system)
>    e_total = system.get_potential_energy()
> 
> i expected that calling SumCalculator with atoms=system would set the
> atoms object of the new SumCalculator object. but it does not (not
> exactly sure why? is that a feature?)!
> in other words, after setting
> 
>   sumcalc = SumCalculator([dft, d4], atoms=system)
> 
> sumcalc.atoms is still None, which then triggers the above unwanted
> behavior.
> 
> Solution:
> one has to explicitly set the atoms afterwards. i do it this way now and
> all is fine:
> 
>   sumcalc = SumCalculator([d4, dft], atoms=system)
>   system.calc = sumcalc
>   sumcalc.atoms = system
>   e_total = system.get_potential_energy()
> 
> hope this prevents others from searching.
> best greetings,
> 
>    rochus
> 
> 
> --
> 
> 
> Prof. Dr. Rochus Schmid
> Lehrstuhl für Anorganische Chemie II
> Computational Materials Chemistry Group
> Ruhr-Universität Bochum
> Room NC02/30 (Postbox 9)
> D-44780 Bochum
> Tel.:   ++49(234) 32 24166
> Fax:    ++49(234) 32 14174
> Email: rochus.schmid at rub.de
> http://www.rochusschmid.de
> 
> _______________________________________________
> ase-users mailing list
> ase-users at listserv.fysik.dtu.dk
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