How to set the DIPOL in the Berry phase calculation

[hbushubiao]

Dear VASP users，
I do not under the DIPOL clearly. Be glad to get your coach.
• The manual said“DIPOL = center of cell (fractional coordinates)
It is the ionic contribution to the dipole moment in the cell is calculated. When comparing changes in this contribution due to the displacement of an ion, this center should be chosen in such a way that the ions in the distorted and the undistorted structure remain on the same side of DIPOL (in terms of a minimum image convention).
Let us have a look at an example from okuno, how to set the DIPOL for both undistorted and distorted
# for POSCAR undistorted.
1.00000000000000
3.9362552663422279 0.0000000000000000 0.0000000000000000
0.0000000000000000 3.9362552663422279 0.0000000000000000
0.0000000000000000 0.0000000000000000 8.5787917413004742
1 1 2 6
Direct
0.0 0.0 0.00
0.0 0.0 0.50
0.5 0.5 0.25
0.5 0.5 0.75
0.5 0.5 0.00
0.5 0.5 0.50
0.5 0.0 0.25
0.0 0.5 0.25
0.5 0.0 0.75
0.0 0.5 0.75
# POSCAR for distorted.
1.00000000000000
3.9362552663422279 0.0000000000000000 0.0000000000000000
0.0000000000000000 3.9362552663422279 0.0000000000000000
0.0000000000000000 0.0000000000000000 8.5787917413004742
1 1 2 6
Selective dynamics
Direct
0.0000000000000000 0.0000000000000000 0.0 F F T
0.0000000000000000 0.0000000000000000 0.580641528170233 F F T
0.5000000000000000 0.5000000000000000 0.258670031604616 F F T
0.5000000000000000 0.5000000000000000 0.731572992033364 F F T
0.5000000000000000 0.5000000000000000 0.943182345842004 F F T
0.5000000000000000 0.5000000000000000 0.469346215366166 F F T
0.5000000000000000 0.0000000000000000 0.217453532607841 F F T
0.0000000000000000 0.5000000000000000 0.217453532607841 F F T
0.5000000000000000 0.0000000000000000 0.696542229605392 F F T
0.0000000000000000 0.5000000000000000 0.696542229605392 F F T
okuno set (0,0,0)for undistorted and (0.5,0.5,0.5)for distorted.