Description: EDIFFG defines the break condition for the ionic relaxation loop.
If the change in the total (free) energy is smaller than EDIFFG between two ionic steps relaxation will be stopped. If EDIFFG is negative it has a different meaning: In this case the relaxation will stop if all forces are smaller than |EDIFFG| . This is usually a more convenient setting.
EDIFFG does not apply to MD-simulations.