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I am doing a spin-polarized calculation with LDA+U for a 10 atom system.

To optimize the atomic postitions, I am using the settings:
EDIFF = 1e-5
EDIFFG = -1e-4
NSW = 200
ISIF = 2
IBRION = 2

However, the calculation terminates after a small number, ~20-50, of iterations while the largest magnitude total force on an atom is larger than 1e-4 eV/Angstrom. For example, it may quit after 24 iterations while the force on a given atom is -0.03 eV/Angstrom. My understanding, based on the manual, is that this calculation should not stop until the absolute value of the largest force is smaller than 1e-4 eV/Angstrom.

Please could you help explain, why might the calculation be stopping before EDIFFG is reached?

Thanks for your help,
AH

did you use selective dynamics? If so, the forces on the atoms which are kept fixed are not considererd when checking the convergence

Thank you for your response.

No, I didn't use selective dynamics.

Is there any other information I could give you about my problem that might help suggest an answer?

Also, does anyone else have this problem?