[QE-users] Berry Phase summary of polarization and conductivity

[Rameswar Bhattacharjee]

Hi Everyone,
I am trying to understand the output for the berry phase calculation
and polarization value. I got the summary results for the two systems
below.

System 1 has a higher band gap material and should be less conductive
whereas system 2 is expected to be higher conductive material. I am
not sure how to connect this hypothesis with the results obtained from
the "lberry= .true" calculator. Any advice would be appreciated.
Thanks



--------------------------------------------------
System 1

                               SUMMARY OF PHASES

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


                          Ionic Phase: -0.15144 (mod 1)

                     Electronic Phase: -0.84847 (mod 2)

                          TOTAL PHASE: -0.99992 (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 = -13.0594703  (mod  13.0605710)  (e/Omega).bohr


           P =  -0.0012445  (mod   0.0012446)  e/bohr^2


           P =  -0.0711483  (mod   0.0711543)  C/m^2


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



               ==================================================


System 2


                               SUMMARY OF PHASES

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


                          Ionic Phase: -0.11151 (mod 1)

                     Electronic Phase:  0.10377 (mod 2)

                          TOTAL PHASE: -0.00774 (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 =  -0.1013519  (mod  13.1023458)  (e/Omega).bohr


           P =  -0.0000054  (mod   0.0007001)  e/bohr^2


           P =  -0.0003096  (mod   0.0400243)  C/m^2


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


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

-- 
Rameswar Bhattacharjee
Postdoctoral Scholar
Georgetown University
Washington, DC 20057