ABINIT Discussion Forums

Dear all,
i'm calculating polarization of Bifeo3 and i have studied its tutorials but in abinit test/v5/t12.in and tests/v5/t12.in.FromPHermet i have these input files to calculate
Berry Phase polarisation:
Input(t12.in):
acell 3*4.62 angstrom
rprim 0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0

#Atom definition
#***************
natom 2
ntypat 2
znucl 11 9
typat 1 2

#SCF parameters
#**************
iscf 17
nstep 1


#Planewave basis
#***************
pawecutdg 80.

ecut 40.
kptopt 3
ngkpt 2 2 2
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
toldfe 1.0d-12

# Berry phase calculation of the polarization
#********************************************
berryopt -1
rfdir 1 1 1

xcart 1.0000000000E-02 0.0000000000E+00 0.0000000000E+00
4.3652673487E+00 4.3652673487E+00 4.3652673487E+00

nbdbuf 0

and Input(t112.in.FromPHermet):
acell 3*4.62 angstrom
rprim 0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0

#Atom definition
#***************
natom 2
ntypat 2
znucl 11 9
typat 1 2

#SCF parameters
#**************
iscf 17
nstep 100


#Planewave basis
#***************
usepaw 1
pawecutdg 80.

ecut 40.
kptopt 1
ngkpt 6 6 6
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
toldfe 1.0d-12

# Berry phase calculation of the polarization
#********************************************
berryopt -1
rfdir 1 1 1

ndtset 3
jdtset 1 2 3

xcart1 0.0000000000E+00 0.0000000000E+00 0.0000000000E+00
4.3652673487E+00 4.3652673487E+00 4.3652673487E+00

xcart2 1.0000000000E-02 0.0000000000E+00 0.0000000000E+00
4.3652673487E+00 4.3652673487E+00 4.3652673487E+00

xcart3 -1.0000000000E-02 0.0000000000E+00 0.0000000000E+00
4.3652673487E+00 4.3652673487E+00 4.3652673487E+00



nbdbuf 0

would you please guide me which input we have to use to calculate Berry phase calculation of polarization?
Best regards.

All you need to compute polarization with Berrys phase is

berryopt -1
rfdir 1 1 1

In these files, the polarization is being computed as a function of atomic displacement, which gives in addition a finite differences approach to computation of the Born effective charges.