[gpaw-users] Saving and restart with custom external potential

[Jens Jørgen Mortensen]

On 1/18/19 3:47 PM, Capiod, P.C.B. (Pierre) via gpaw-users wrote:
>
> Hi all,
>
> I have tried to add a custom external potential (an image potential in 
> the form -1/z). The write of the .gpw reported an error in the 
> beginning until I added "def todict(self):" with a proper definition.
>
> Here is the script added for the ImagePotential:
>
> class ImagePotential(ExternalPotential):
>     def calculate_potential(self, gd):
>         grid = gd.get_grid_point_coordinates()
>         self.vext_g = 1 / (4*(grid[2] - (zpos-wall)))
>
>     def todict(self):
>         return {'name': 'ImagePotential',
>                 'potential': self.vext_g}
>
> This is in a similar fashion as the example provided for the harmonic 
> potential.
>
> Unfortunately I cannot reload the .gpw created with this modification.
>
> The error is the following:
>
> Traceback (most recent call last):
>   File "Cu111_1.51.py", line 90, in <module>
>     convergence={'bands': 'occupied'})
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/calculator.py", 
> line 146, in __init__
>     atoms, **kwargs)
>   File 
> "/usr/lib/python3.7/site-packages/ase/calculators/calculator.py", line 
> 362, in __init__
>     self.read(restart)  # read parameters, atoms and results
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/calculator.py", 
> line 220, in read
>     self.initialize(reading=True)
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/calculator.py", 
> line 692, in initialize
>     self.create_hamiltonian(realspace, mode, xc)
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/calculator.py", 
> line 906, in create_hamiltonian
>     pd2=dens.pd2, pd3=dens.pd3, realpbc_c=self.atoms.pbc, **kwargs)
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/wavefunctions/pw.py", 
> line 1546, in __init__
>     redistributor=redistributor)
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/hamiltonian.py", 
> line 95, in __init__
>     vext = create_external_potential(**vext)
>   File 
> "/home/pierre/.local/lib/python3.7/site-packages/gpaw/external.py", 
> line 17, in create_external_potential
>     return globals()[name](**kwargs)
> KeyError: 'ImagePotential'
>
> Any idea how I can solve this issue ?
>

There is no good way to do that at the moment.  It might work if you 
register your potential class like this:

import gpaw.external as ext
ext.__all__.append('ImagePotential')
ext.ImagePotential = ImagePotential


before reloading.


Jens Jørgen


> Best regards,
> Pierre
>
>
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