[Wannier] Wannier function under applied electric field

[Stepan Tsirkin]

Dear Chandan,

Sure, the electrons interact with the electric field, and hence the 
Wannier functions shift. In other words, the field breaks the symmetry 
the pins the centers of the WFs to the atoms.  There is not option to 
fix the center precisely.

However, It is suspicious that the spread changes too much? If you start 
gradually increasing the field, do the spreads change continuously, or 
is there a jump. If there is a jump, then probalby there is some issue 
with wannierization, e.g. windows need to be adjusted.

Regards,

Stepan.

On 14.12.20 05:59, Chandan Singh wrote:
>
> Dear Wannier90 users and developers,
>
> Recently I did a Wannier90 calculation for the 2D material under the 
> applied electric field along z-direction using atom centered Wannier 
> function (WF) to interpolate the DFT band structure correctly. I 
> observe some of the WFs shifted from the initial position and have a 
> larger spread. The total spread of WFs is nearly double with respect 
> to without electric field calculation.
> I have some queries related to this topic.
>
> 1. Can the center of Wannier function shift under the electric field?
>
> 2. Is it possible to fix the center of Wannier function in Wannier90 
> calculations?
>
> Sincerely,
> Chandan Singh
> PhD Student
> Department of Physics
> IISER Pune, India
>
>
>
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