?
Dear Developers,
I am a new user of Espresso-4.0 and when I ran the example10
(polarizayion of cubic PbTiO3 via Berry phase calculation)I found that the
total ionic phase is not the sum of the ionic phases of the individiual
constituents i.e Pb ,Ti ,O but in the tetragonal PbTiO3 the total ionic phase
is -0.22375 which is the individual sum of Pb ,Ti, O.
I am attaching the O/P files (only a section as the
complete file is bulky)of cubic and tetra phase of PbTiO3 ( polarization
calculation ) for comparison.
I would be really thankful for any explanations or
reasoning in this context.
FOR CUBIC PHASE
IONIC POLARIZATION
~~~~~~~~~~~~~~~~~~
Note: (mod 1) means that the phases (angles ranging from
-pi to pi) have been mapped to the interval [-1/2,+1/2) by
dividing by 2*pi; (mod 2) refers to the interval [-1,+1)
============================================================================
Ion Species Charge Position Phase
----------------------------------------------------------------------------
1 Pb 14.000 0.0000 0.0000 0.0100 0.14000 (mod 2)
2 Ti 12.000 0.5000 0.5000 0.5000 0.00000 (mod 2)
3 O 6.000 0.0000 0.5000 0.5000 -1.00000 (mod 2)
4 O 6.000 0.5000 0.5000 0.0000 0.00000 (mod 2)
5 O 6.000 0.5000 0.0000 0.5000 -1.00000 (mod 2)
----------------------------------------------------------------------------
IONIC PHASE: 0.14000 (mod 2)
============================================================================
FOR TETRAGONAL PbTiO3
IONIC POLARIZATION
~~~~~~~~~~~~~~~~~~
Note: (mod 1) means that the phases (angles ranging from
-pi to pi) have been mapped to the interval [-1/2,+1/2) by
dividing by 2*pi; (mod 2) refers to the interval [-1,+1)
============================================================================
Ion Species Charge Position Phase
----------------------------------------------------------------------------
1 Pb 14.000 0.0000 0.0000 0.0100 0.13142 (mod 2)
2 Ti 12.000 0.5000 0.5000 0.5377 0.05689 (mod 2)
3 O 6.000 0.5000 0.5000 0.1118 0.62968 (mod 2)
4 O 6.000 0.0000 0.5000 0.6174 -0.52267 (mod 2)
5 O 6.000 0.5000 0.0000 0.6174 -0.52267 (mod 2)
----------------------------------------------------------------------------
IONIC PHASE: -0.22735 (mod 2)
============================================================================
Thanking You
SATHYA SHEELA.S
Grad. Student
Department of Physics
National Institute of Technology
Tiruchirapalli - 620015
India
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