[Smeagol-discuss] Total Energy

[Ivan Rungger]

Hello Simon,
> Ok. However, if the size of the cell is well converged (i.e. the bulk like
> hartree potential is recovered in the last principal layer) it shouldn't
> affect the result. Does it?
>   
No, in fact I think that in principle the smeagol total energy is OK. In
practice however due to the sensitivity of the energy on the variation
of the charge I think it has to be taken with care.
> So, you are not puzzled by the absence of the self-energies in the total
> energy calculation ? I am planning  to do some tests in order to see
> whether the E_self term cancel or not....
>   
I think that term does not have to be added. Moreover, since the
self-energies are energy-dependent, it would be an energy integral (if
one has to add it). Having said that it might be possible to obtain some
total energy based on the self-energies (which would be interesting),
but I don't know.

Another thing: assuming that the unit cell is repeated periodically one
can calculate the total energy per unit cell by implicitly dividing the
energy of the whole system by the number of cells (which goes to
infinity for the periodic system); however if the system is not periodic
(e.g. semi-infinite), the energy of a sub-part of this system  is not
really defined I think.

Cheers,

Ivan
> Simon
>
>