<div dir="ltr">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. </div>