[Wien] TOT ENE -> Vacancy formation energy

[MARC CAWKWELL]

You have to include for the fact that you have different number of atoms
in your two calculations.

The vacancy formation energy is:

E_vac = ((N-1)/N)*E_tot(N) - E_tot(N-1)

Where N is the total number of atoms in the block without the vacancy:
E_tot(N) is the total energy of the system without the vacancy and
E_tot(N-1) is the total energy of the system with the vacancy. Your 100 Ry
is probably the energy of the atom you removed.

Hope this helps,

Marc


On Mon, 15 Nov 2004, fabella wrote:

> Hello,
>
> I'm working on a vacancy calculation.  There are two calculations
> involved!  One for the ideal crystal and the other with the vacancy.
> The struct files are identical except the one for the vacancy an atom
> is removed.
>
> Here is my question / problem
>
> The Total ENE difference between the ideal crystal and the crystal with
> vacancy is not physical (over 100 Ry).  Obviously there seems to be a
> problem. (Within the crystal with vacancy calculation the relaxation
> energy is about 1.3 eV for Silicon vacancy, i think this is decent)
>
> These are some factors related.
> RKmax reduced to 6.05 (consistent for both)
> WEIGHT 4.0 for vacancy / 2.0 for ideal  ( What is this "WEIGHT" factor?
> )
>
> Other than that what could make these Energies with respect to the
> given crystals so different (over 100 Ry)?
>
> Thank You
> Wesley J Fabella
>
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