[Pw_forum] what is w1 and w2 for bfgs relaxed calculation

[Paolo Giannozzi]

On Apr 25, 2007, at 7:32 , yukihiro_okuno at fujifilm.co.jp wrote:

> I met not conserved force

"not converged", I guess.

> in relaxed calculation for slightly titled crystal structure for PZT

Are you referring to the following:
http://www.democritos.it/pipermail/pw_forum/2007-April/006311.html ?
This behavour might simply mean that the structural optimization is not
converged;  or that the scf convergence towards the end of the
structural optimization is not sufficient to get forces with high  
accuracy;
finally, it might also signal some inconsistency between the calculated
energy and the calculated forces. You may test for the latter by
calculating forces as numerical derivatives of the energy with respect
to atomic displacements (it is better to try this in simple systems).
If you notice serious discrepancies, please report them to the list

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy