I am interested in knowing the electrostatic potential in specific regions of the Brillouin zone of an ab initio calculation where an external electric field was applied to a bilayer system perpendicularly. The intention is to calculate the potential drop the system sees for those specific states of interest. I am using QE for the calculations. I saw that pp.x offers the electrostatic potential for the entirety of the system. However, I am not sure how helpful would be in this case as the effect I study occurs around one symmetry point of the upper valence band, and the charge distribution over the whole momentum space for that energy level behaves quite differently under the applied electric field.
Is there any way to extract the electrostatic potential per energy state and kpoint?
In case is relevant, I am used to working with the wavefunctions files, but I am not sure in what way the electrostatic potential is calculated by QE (I am not so experienced with Fortran) in case the only way is calculating it manually.
Thank you for your time.