[Pw_forum] conv_thr for forces for relaxing ions

Madhura Marathe madhura at jncasr.ac.in
Wed Apr 22 10:30:45 CEST 2009

 Dear all,

 During one of the ionic relaxation calculations, I got the error message,
"SCF correction compared to forces is too large, reduce conv_thr". I am
using conv_thr = 1.0d-8 which is generally sufficient, so I increased the
parameter upscale (from 10.0 to 100.0) in &IONS to reduce the the
threshold during relaxation. This lead to the convergence till the last
ionic iteration which was converged to sufficient accuracy, when again the
same error message occurred. The forces then are
     Total force =     0.000136     Total SCF correction =     0.000016
     SCF correction compared to forces is too large, reduce conv_thr

 There has been a recent discussion on the topic. From that, I gathered
that the subsequent relaxations after this error message are not
 So my question is whether the forces are reliable in this last iteration?
Or do I need to further reduce the conv_thr and re-run the whole

 Thanks for the help,

Madhura Marathe,
PhD student, TSU,
JNCASR, Bangalore.
Phone No: +91-80-22082835

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