Question about electric field in bulk structure

[PSChen]

Hi
              I want to add an electric field in the specific direction for a bulk(period system) and try to optimize.
        How to modify the editor? thank you very much.

[Petr Khomyakov]

Take a look at this tutorial: https://docs.quantumwise.com/tutorials/opening_a_band_gap/opening_a_band_gap.html.

[PSChen]

thanks for your reply.
I have some questions for this tutorials.
1. For silicene structure, I try to optimize the structure after insert the metallic gates and make the different result(Both for 0V/nm and 4V/nm).
   What difference for the geometry with and without the spatial region.
2. If I want to add the field along the in-plane direction and optimize the structure. How can I set the calculation?
    Can I know the path of atom movement under electric field by NEB?

thank you very much.

[Anders Blom]

1. Difference? The field, obviously... Oh you mean with/without electrode (even at zero bias). It could depend on the distance, if the electrodes are close to the silicene, since they change the boundary condition at the edge of the simulation cell from periodic to Neumann.

2. There is a very complicated way to do that, using Born effective charges, which I will not go into there, but you can make a "slab-like" configuration of the silicene and use the same setup with metal electrodes to create an in-plane field.