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Calculation ends before EDIFFG is reached

Posted: Wed Jul 11, 2007 5:17 pm
by ajhatt
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

Calculation ends before EDIFFG is reached

Posted: Tue Jul 31, 2007 8:59 am
by admin
did you use selective dynamics? If so, the forces on the atoms which are kept fixed are not considererd when checking the convergence

Calculation ends before EDIFFG is reached

Posted: Tue Aug 14, 2007 4:46 pm
by ajhatt
Thank you for your response.

No, I didn't use selective dynamics.

Calculation ends before EDIFFG is reached

Posted: Mon Sep 03, 2007 9:59 pm
by ajhatt
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?