What is the deformation potential reference energy

Dear Alex,
I have a question related to the deformation potential constant.
While calculating the deformation potential, what reference energy
state was considered while calculating the change in the absolute band
positions as a function of strain? This reference state can be very
crucial in determining the deformation potential.

Please make a reference to Fermi Level. I have double checked it.

Dear GAO,
Thank you for your reply. Can you explain in more detail? How you take the Fermi level as a reference?

Hi Aamir,

In the amset deform tool, there are three potential reference levels depending on the system and the calculation settings:

For semiconductors/insulators (i.e., when the band gap != 0), the reference level is taken from either:

  1. The average electrostatic potential at the atomic cores (written by default in the OUTCAR). The average value across all atoms is used as the reference.
  2. The core level eigenvalues (used if ICORELEVEL = 1). Again, the average value for all atoms is used. For each atom, the deepest core level is chosen.

For metals:

  1. In metals the Fermi level is used as the reference. See Khan and Allen, Phys. Rev. B, 29 (1984) 3341 for more details.

I hope that answers your question.


Dear Aamir,

Especially, the energy is E-Ev. Ev is the absolute value of the vacuum. the x-axis is the delta_strain/L0. L0 is the unstrain length. Then you can use a linear fit to get the deformation potential constants as you like. More details can be found: DOI: 10.1021/acsami.8b11836

Best wishes,