[QE-users] Calculation of Polarization using berry phase rule

[Pankaj Sahota]

Hi

I am new to the field of ferroelectrics. To test my procedure of calculations, I was trying to reproduce your PRL paper on NbN monolayers (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.037601 <https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.037601>). I am following the steps as described by Quantum espresso example file on PbTiO3. But with this method, I am getting really weird numbers for polarization (really large numbers are coming). Also QE write the results C/m^2. That means it is dividing the dipole moment by volume. Is QE using the volume of the unit cell which includes vacuum also.

 

Could you please help me in figuring out where am I going wrong? I attached my scf input file and the non-scf input and output files to calculate the polarization by implementing berry phase rule. The files b1, and b2 corresponds to the direction of polarization along x and z-direction.








 

I would really appreciate your help.
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