[QE-users] Zak Phase (Z2 invariant) computation

[Rameswar Bhattacharjee]

Hi Chiara,
Thank you very much for your response and the suggestions. In the mean
time I found a way to calculate berryphase in QE using "lberry=.true"
along the specified direction. The outputs prints like below

-------------------------


                               SUMMARY OF PHASES

                               ~~~~~~~~~~~~~~~~~


                          Ionic Phase:  0.36908 (mod 1)

                     Electronic Phase:  0.61352 (mod 2)

                          TOTAL PHASE:  0.98260 (mod 1)



                             VALUES OF POLARIZATION

                             ~~~~~~~~~~~~~~~~~~~~~~


        The calculation of phases done along the direction of vector 1

        of the reciprocal lattice gives the following contribution to

        the polarization vector (in different units, and being Omega

        the volume of the unit cell):


           P =  13.5181184  (mod  13.7574631)  (e/Omega).bohr


           P =   0.0006879  (mod   0.0007001)  e/bohr^2


           P =   0.0393280  (mod   0.0400243)  C/m^2


        The polarization direction is:  ( 1.00000 , 0.00000 , 0.00000 )
----------------------------------------------------

Do you have any idea if this can be connected to Z2 invariant in Zak
phase for 1D system?

Any suggestion from other experts would be highly appreciated.

Thanks
Rameswar