spontaneous polarization using vasp 5.2

[wmh]

May I ask you a question about ferroelectric dipole moment calculation?
I did not attach INCAR or other files because I follow exactly same
example in below links.
In vasp there are two ways of calculating FE dipole moment:

http://cms.mpi.univie.ac.at/vasp/vasp/L ... again.html
http://cms.mpi.univie.ac.at/vasp/vasp/L ... _tags.html

on the links there are example of
NaF
4.5102
0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
1 1
Direct
0.0000000000000000 0.0000000000000000 0.0000000000000000
0.5000000000000000 0.5000000000000000 0.5000000000000000


and I can get the same results:
electronic dipole moment: p[elc]=( 0.00000 0.00000 0.00000
) electrons Angst

If we move all atoms by same vectors, the dipole moment should not
change, right? So I tried the following,
NaF
4.5102
0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
1 1
Direct
0.0000000000000000 0.0000000000000000 0.0100000000000000
0.5000000000000000 0.5000000000000000 0.5100000000000000



But the results now change! Becomes:
macroscopic dipole moment: p[mac]=( 0.36081 0.36081
0.00000 ) electrons Angst

I tried moving all atoms by other vectors and they all change. So if
we calculate PVDF's moment,
we put one PVDF wire in a supercell, I will get different results
depending on where I put it in
supercell: center or margin leads to completely dipole moment.

,do I misunderstand
something? Thank you very
much and your help is highly appreciated!

[support_vasp]

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