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[Enrico <enrico.avenati@gmail.com>]

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