[Pw_forum] (no subject)

Paolo Giannozzi giannozz at nest.sns.it
Tue Aug 3 18:22:11 CEST 2004

On Wednesday 28 July 2004 08:49, Raghani Pushpa wrote:

> though the energy is not decreasing further from
> 9th to 37th iteration but the code is still running, 
> it does not stop. could u please tell me why is it 
> happening? 

there are two convergence criteria for stopping a structural
optimization: one on the magnitude of forces (forc_conv_thr), 
one on the change of the energy wrt the previous iteration
(etot_conv_thr). Both have to be satisfied. If the calculation
doesn't stop, it is because at least one of the two is not satisfied.

I am not actually sure that the check on the magnitude of forces
works properly if you have constraints (i.e. checks only forces on
atoms that can move). If it doesn't, set forc_conv_thr to a large value


Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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