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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi, 

The total energy is defined up to a constant This removes most interest from the comparison you are doing. Also, the number of valence electron included in the computation will matter a lot for the result you get: try with Abinit the a single xc and a pseudopotential with 1 or 11 e- for Cu you'll see  the same kind of difference in total energy you witness here between Abinit and Vasp since in one case you consider the energy of a single e- and in the other the energy of 11 e-.

If you want to make accurate comparison between Vasp and Abinit calculations, you may want to consider derivative of energy: elastic constant, forces ...
Or physical parameters like lattice constant. 

regards

PMA

On Tue, Apr 1, 2008 at 3:17 PM, Enrico <enrico.avenati@gmail.com> wrote:

Hi,
i'm running ground state calculation of Cu FCC with abinit v.5.3.4
I did LDA (icx=1)  GGA (ixc=11) and got two completely different result!

One LDA (according with some VASP calculation)  etotal   - .51046456 Ha,
the second GGA  much much bigger                        etotal   -42.71596 Ha.

Same input obviously, i changed the pseudopotential and IXC, that's all.
LDA 29cu.1.hgh pseudo
GGA 29-Cu.GGA.fhi

Here follow the input
#UNIT CELL
acell 3*3.6148 Angstr
rprim  0.0  0.5  0.5   # Real space PRIMitive translations
      0.5  0.0  0.5
      0.5  0.5  0.0
ntypat 1
znucl  29
natom  1  # atom per cell
typat  1  # this atom is of type 1 ( ntypat 1) in this case Cu
xred
0.0 0.0 0.0

#RECIPROCAL SPACE INTEGRETION
kptopt 1
nshiftk 4            # shiftk=4 particular efficient for FCC
shiftk 0.5 0.5 0.5
      0.5 0.0 0.0
      0.0 0.5 0.0
      0.0 0.0 0.5
ngkpt 6 6 6
nband 18
tsmear 0.02
occopt 4

#PLANE WAVES
ecut 20

#SCF PROCEDURE
nstep 30
ixc 11
toldfe 1.0d-7

If could help me thanks  a lot

-- 
Pierre-Matthieu Anglade