[Pw_forum] Slab optimization with -24kbar stress!!!

[Nicola Marzari]

On 04/12/2014 19:26, David Foster wrote:
> As you see final stress is -24.51 kbar ??????!!!!!!!!!!!!!!
> As you know, for slab, we don't used "vc-relax", and only optimize ions positions. What should I do to reduce the stress on the slab?


The stress is the derivative of the energy with respect to strain.
If it's not zero, you need to strain (i.e. relax) the cell.

Maybe less punctuation, as well.

			nicola

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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL