[Pw_forum] Slab optimization with -24kbar stress!!!
paolo.giannozzi at uniud.it
Thu Dec 4 21:10:30 CET 2014
On Thu, 2014-12-04 at 10:26 -0800, David Foster wrote:
> My main problem is final section of the output:
> total stress (Ry/bohr**3) (kbar) P= -24.51
> -0.00007691 0.00000000 -0.00000000 -11.31 0.00 -0.00
> 0.00000000 -0.00032173 0.00000000 0.00 -47.33 0.00
> -0.00000000 0.00000000 -0.00010117 -0.00 0.00 -14.88
> As you see final stress is -24.51 kbar ??????!!!!!!!!!!!!!!
Maybe the explanation is here ??????!!!!!!!!!!!!!!
Before the last step, the code should have printed the following
A final scf calculation at the relaxed structure.
The G-vectors are recalculated for the final unit cell
Results may differ from those at the preceding step.
If your plane-wave basis set is not very converged, and if your
final unit cell volume is significantly different from the starting
one, you may easily get a few tens of kBar as final pressure
(corresponding to a very small change in volume anyway)
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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