[Pw_forum] add vacuum

[stefano de gironcoli]

is your system a free-standing thin film or aims at representing a surface ?

in the former case you need to relax (only in the xy plane), in the 
latter the in-plane lattice parameters should be fixed to the 
(theoretical)bulk values of your system.

stefano


On 11/12/2015 09:33, Jaret Qi wrote:
> Hello QE users,
> I need to add vacuum along the z-direction to study E-field effect 
> using saw-like potential. In this case do I need to do vc-relax or 
> relax will be enough?
>
> Thank you in advance,
> Jaret
> ASU
>
>
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