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Hi,

I want to calculate how the vibrational properties of bulk perovskite oxides change under an electric field. To do that, I run MLFF MD (ML_MODE = run) with the INCAR EFIELD tag on. My question is, do I always have to create a vacuum in the direction of the external electric field? What happens if I just apply an electric field without a vacuum? I'm worried if I insert a vacuum layer, the surface effect will dominate and get rid of the electric field effect.

Best,
Inhwan

Hi Inhwan,

Thanks for reaching out. External electric fields do not make sense in a 3D bulk system. The homogeneous electric field would not create any net effect in a periodic system. That is why the use of EFIELD should be restricted to slabs and molecules. The surface effects are an important part of the physics in this case.

I hope that I was able to answer your question.

Totally!

Thank you for your response.

Inhwan