[gpaw-users] How can the vacuum potential be found out

[Georg Kastlunger]

Dear Ask,

thank you very much for the answer!

I have already tried to print the potential and it worked well.

As usual one answer leads to two new questions:

The first one is quite simple. Which units are used in the output of the 
effective potential?
The second one deals with the definition of the effective potential. Is 
the effective potential calculated as the sum of Coulomb and XC 
potential or is it something else?

Thanks in advance
Best regards Georg



On 02/06/2012 02:07 PM, Ask Hjorth Larsen wrote:
> Hi
>
> On Mon, 16 Jan 2012, Georg Kastlunger wrote:
>
>> Hello community,
>>
>> I would like to calculate some orbital energies relative to the vacuum
>> potential (the average Hartree potential in the vacuum) of my cell.
>> I have already searched through the tutorial pages, but i couldn't find
>> out how I can find the value of the vacuum potential.
>>
>> My question now is: Does anyone know an implementation, which makes it
>> possible to print out this potential?
>> Or otherwise can the average of the Coulomb potential in the vacuum
>> somehow be calculated in gpaw?
>>
>> Another very important point would be the reference energy and the units
>> of the potential printed in the output.
>>
>> Thanks in advance to everyone!
>> Georg
>
> Well, the effective potential is stored here:
>
>   calc.hamiltonian.vt_sG
>
> This is indexed by spin and grid point, e.g. vt_sG[0, 43, 14, 23] is a 
> number.
>
> However if you use a non-periodic cell the boundary conditions are by 
> default zero, meaning that the potential far away is exactly zero.
>
> Regards
> Ask
>
>