[Wien] Total energy

[Laurence Marks]

I believe that the energy WIen2k gives is an approximation to the
total energy to decompose the system into bare nuclei and free
isolated electrons in vacuum, whereas a pseudopotential method gives
the energy to decompose the system into "pseudo-cores" (i.e. with some
electrons) and remove all the valence electrons to vacuum.

On Tue, Feb 3, 2009 at 6:23 AM, Stefaan Cottenier
<Stefaan.Cottenier at ugent.be> wrote:
>
>> I am calculating a bulk structure with 9 atoms (4 inequivalent atoms) in one unit cell.
>> In the reference, the total energy of on unit cell is -54.06 eV (PRB 74,35414 2006), but the total energy I find in scf file is about -20302 Ry.
>> Why the total energy is so different?
>
> I did not check that reference, but very likely it is a pseudopotential
> calculation. Pseudizing away the core means that the large core
> contributions to the total energy disappear as well. Total energies from
> pseudopotential calculations and all-electron calculations cannot be
> compared with each other (but energy *differences* within each method can).
>
> Stefaan
>
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-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering to study the structure of matter.