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Forces of previously relaxed geometry, should they be zero?

Posted: Mon May 05, 2014 9:17 am
by hosfa
Hi,
I relaxed a geometry with regard to the forces less than 0.0001
I again ran a calculation with the final CONTCAR with every tag in INCAR the same as previous one except for NSW=0!
But I got huge forces: .gt. 0.01
What is behind this?

Forces of previously relaxed geometry, should they be zero?

Posted: Tue May 06, 2014 7:29 am
by admin
did the cell volume / shape change as well during your first run as well?
If so, a different basis set is initialized in the new run, which may lead to
larger forces again, depending on the change of the basis set

Forces of previously relaxed geometry, should they be zero?

Posted: Sat May 17, 2014 9:53 am
by hosfa
[quote="admin"]did the cell volume / shape change as well during your first run as well?
If so, a different basis set is initialized in the new run, which may lead to
larger forces again, depending on the change of the basis set
[/quote]

Thanks a lot!
In may relaxation run(NSW=100) the cell shape and volume remained the same! Moreover the position of the atoms remained the same as well. (the initial geometry was relaxed, and I just increased the accuracy, KPOINTS,... to be on the safe side!)
But when I use the same incar with NSW=0 I get forces!
Looking forward for your comment.