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

[Georg Kastlunger]

Thanks again for your help,

but unfortunately we are primarily interested in the case of periodic
boundary conditions.

Is there maybe anybody else who might know how the zero energy is
defined in periodic cells?

Regards,
Georg


On 02/06/2012 05:22 PM, Ask Hjorth Larsen wrote:
>  Hi
>
>  On Mon, 6 Feb 2012, Georg Kastlunger wrote:
>
>>  Which boundary do you mean?
>>  Is it the value at one certain point in the cell or an average of an
>>  interface between unit cells?
>>
>>  Best regards,
>>  Georg
>
>  The potential is zero at all the non-periodic cell boundaries.  This
>  means one cannot shift the potential arbitrarily - it is unique, and
>  so are the eigenvalues.
>
>  Each eigenvalue equals the derivative of the total energy with respect
>  to the occupation of the corresponding state (keeping wavefunctions
>  and density constant).
>
>  (The same is not true if the cell is fully periodic; then I'm not sure
>  what determines the potential and eigenvalues)
>
>  Regards
>  Ask
>
>

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