DIFFICULT TO GET A CORRECT INTERPRETATION - CHARGED DEFECTS

[giacomo giorgi]

Dear All,
I am facing this problem.

I optimized BULK GaAs (64 atoms). Then I replaced 1 As with a Germanium atom. I checked that the defect is localized on the substituted atom. Then I calculate the quadrupole moment for the ideal bulk neutral cell setting

IDIPOL=4
DIPOL=0.333 0.666 0.333 (i.e. the coord of the defect)
LDIPOL=False

I get this value

DIPCOR: dipole corrections for dipol
direction 1 min pos 15 value= -0.332059 electrons x Angst
direction 2 min pos 29 value= -1.367929 electrons x Angst
direction 3 min pos 22 value= 0.768969 electrons x Angst
Tr[quadrupol] -2479.727805

energy correction for charged system 0.000000 eV
dipol+quadrupol energy correction 0.054784 eV
extern-ion 0.000000 eV (added to PSCEN)
...
...
free energy TOTEN = -305.904854 eV





THEN
I take into account charged defect -1

I properly set NELECT in the INCAR. IDIPOL, DIPOL and LDIPOL will be the same ones of the uncharged calculation and then I get these results

DIPCOR: dipole corrections for dipol
direction 1 min pos 105 value= 198.351278 electrons x Angst
direction 2 min pos 15 value= 198.351110 electrons x Angst
direction 3 min pos 105 value= 198.351219 electrons x Angst
Tr[quadrupol] -1203.581131

energy correction for charged system 1.814372 eV
dipol+quadrupol energy correction 2513.080425 eV
extern-ion 0.000000 eV (added to PSCEN)
....
....
free energy TOTEN = 2211.853952 eV


for -2 charged defect I get

DIPCOR: dipole corrections for dipol
direction 1 min pos 98 value= 197.636168 electrons x Angst
direction 2 min pos 14 value= 197.635997 electrons x Angst
direction 3 min pos 98 value= 197.636108 electrons x Angst
Tr[quadrupol] -1245.501762

energy correction for charged system 7.208429 eV
dipol+quadrupol energy correction 2477.048258 eV
extern-ion 0.000000 eV (added to PSCEN)
...
...
free energy TOTEN = 2185.368406 eV



Manual says "if no dipole-dipole interaction is present you can simply scale down the energy printed in the line dipol+quadrupol energy by the ratio defect-induced quadrupole/total cell quadrupole"

But this does not seem to be the case. What about in this case? How to treat DIPCOR in the overall calculation?

Thanks in advance.
My best,
G

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