[gpaw-users] Negative atom energies?

[Jens Jørgen Mortensen]

On Mon, 2011-01-17 at 20:08 +0100, Ask Hjorth Larsen wrote:
> Hi Yuelin
> 
> On Mon, 17 Jan 2011, Yuelin Li wrote:
> 
> > With the attached script I have atom energy for O, Ca and Mn at -2,0.2,-5.5, 
> > are they right?
> 
> The best way to check that an atomic calculation is correct is to see that 
> it gets the correct eigenvalues, e.g. by comparing them to the NIST 
> all-electron database (link can be found on the gpaw atomic setup pages).
> 
> In general, please attach the output file also.
> 
> -5.5 seems rather lowish.

The numbers are relative to spin-paired spherically symmetric atoms
calculated with no approximations such as a finite grid spacing.  So, I
think your numbers look OK.  If you look at 

http://physics.nist.gov/PhysRefData/DFTdata/Tables/25Mn.html

You will get (-1148.644093+1148.449372)*27.21 = 5.3 eV for LDA which is
quite close to your 5.5 value for PBE and h=0.2.

Notice that you Mn atom is not centered in the box!

For CMO, shouldn't you calculate 3*e1+e2+e3-e4?

Jens Jørgen

> Regards
> Ask
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