[QE-users] Polarization of 2D Ferroelectric Berry Phase Method

[Atanu Kumar Saha]

Hi all,

I want to calculate the spontaneous polarization of a 2D material using Berry Phase method.
However, I am facing some lacking in understanding the following issues.


  1.  If gdir=3 (z-axis) and nppstr = 5, in this case it will take 5 k-points along z axis. However, for 2D materials kz should be 0. What does it mean by k string along reciprocal of z-axis. I tried with nppstr=1. The simulation fails.
  2.  What is the difference between the 'polarization calculated by iberry=.true' and  electronic dipole calculated by lelfield=.true' ? Are they same?
  3.  What is the difference between electronic dipole and Ionic dipole reported during lelfield  = .true calculation?

Thanks in advance.

Atanu K Saha
Ph.D. Candidate
ECE, Purdue University

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