SCF energy not identical to result of final energy of geometry optimization

[Frank von Horsten]

Dear all,

I am recalculating the SCF energy of a previously optimized geometry. 
However, the results of the single point calculation differ quite 
significantly from the final energy of the optimization.

More specifically, the final energy of the geo opt reads 
E=-3578.782615929515032. This is the final in the line "ENERGY| Total 
FORCE_EVAL" line. Already here the energy is slightly different from the 
subsequent "Reevaluating energy at the minimum" part.
There the SCF cycle gives -3578.782584007462901. Admittedly, that is only 
0.084 kJ/mol but still I find this a bit strange.dir

When I use the same input file just changing GEO_OPT to ENERGY_FORCE and 
taking the final structure of the optimization I get an energy of 
-3578.778182659758386, which is lower by 11.5 kJ/mol.

Also the calculated forced differ. For the optization the last forces are
SUM OF ATOMIC FORCES          -0.00006050    -0.00001418    -0.00343851     
0.00343908

Whereas for the single point calculatin I get
SUM OF ATOMIC FORCES          -0.00000811    -0.00001851    -0.01197202     
0.01197204

The system is a 4x4 Cu(100) slab (64 Cu atoms) with a c(2x2) chloride 
adlayer on top (8 Cl atoms) and eight Na atoms as counter ions in the 
vacuum region.

Does anyone have an idea where these discrapancies come from?

Cheers,

Frank

PS: I have attached the input and output files in case someone wants to 
take a closer look.


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