Dipol moment clarification

[tanggara]

Hi everyone!

I have been trying to calculate dipole moment (+vibrational frequency) and been getting really weird result from 2 very similar structures (with 0.001 eV difference). My INCAR goes:

ISTART = 0
ICHARG=2
ISPIN=2
MAGMOM=11*0.0 24*0.0 -2.0 5*-3.0
ENMAX = 400
ISMEAR = 0
SIGMA = 0.2
PREC=High
EDIFF=1E-8
EDIFFG=-0.010
ISIF=2
NFREE=2
IDIPOL=4

LREAL=A
ROPT=7*0.0005
ALGO = F

NSW=1

IBRION = 5
POTIM = 0.010
LWAVE=.FALSE.
LVTOT=.FALSE.
LCHARG=.FALSE.

Using 1x1x1 KPOINTS: The first one will give me dipolmoment of:

dipolmoment 10.931774 -7.270266 17.838502 electrons x Angstroem
dipolmoment 15.214327 -1.771909 22.643152 electrons x Angstroem
dipolmoment 20.370813 -1.778793 22.648980 electrons x Angstroem
dipolmoment 20.379301 -1.774195 22.647456 electrons x Angstroem
dipolmoment 20.376282 -1.778997 22.649379 electrons x Angstroem
dipolmoment 20.378069 -1.776491 22.652172 electrons x Angstroem
dipolmoment 20.377508 -1.776673 22.644576 electrons x Angstroem
dipolmoment 20.382644 -1.775603 22.650403 electrons x Angstroem
dipolmoment 20.372875 -1.777598 22.646301 electrons x Angstroem
dipolmoment 20.378637 -1.774562 22.647661 electrons x Angstroem
dipolmoment 20.377002 -1.778635 22.649159 electrons x Angstroem
dipolmoment 20.378157 -1.777772 22.655747 electrons x Angstroem
dipolmoment 20.377386 -1.775464 22.641085 electrons x Angstroem
dipolmoment 20.358595 -1.781354 22.643616 electrons x Angstroem
dipolmoment 20.396450 -1.771946 22.652789 electrons x Angstroem
dipolmoment 20.374258 -1.781000 22.649991 electrons x Angstroem
dipolmoment 20.381303 -1.772220 22.646787 electrons x Angstroem
dipolmoment 20.374681 -1.775799 22.632180 electrons x Angstroem
dipolmoment 20.380578 -1.777486 22.664392 electrons x Angstroem
dipolmoment 20.375488 -1.774249 22.653085 electrons x Angstroem
dipolmoment 20.379492 -1.779000 22.643575 electrons x Angstroem
dipolmoment 20.378341 -1.775250 22.648780 electrons x Angstroem
dipolmoment 20.377320 -1.777927 22.648100 electrons x Angstroem
dipolmoment 20.380626 -1.775318 22.651336 electrons x Angstroem
dipolmoment 20.374904 -1.777875 22.645331 electrons x Angstroem

if I grab all the dipolmoment flag from the OUTCAR, while the other one will give me:

dipolmoment 11.889652 -1.264499 18.199579 electrons x Angstroem
dipolmoment 16.556943 3.839344 18.192681 electrons x Angstroem
dipolmoment 16.547218 3.837363 18.188559 electrons x Angstroem
dipolmoment 16.552972 3.840475 18.190019 electrons x Angstroem
dipolmoment 16.551301 3.836244 18.191339 electrons x Angstroem
dipolmoment 16.552373 3.837245 18.197990 electrons x Angstroem
dipolmoment 16.551807 3.839431 18.183382 electrons x Angstroem
dipolmoment 16.558813 3.840601 18.189988 electrons x Angstroem
dipolmoment 16.545365 3.836132 18.191297 electrons x Angstroem
dipolmoment 16.553575 3.840770 18.189697 electrons x Angstroem
dipolmoment 16.550645 3.835948 18.191676 electrons x Angstroem
dipolmoment 16.552330 3.838487 18.194021 electrons x Angstroem
dipolmoment 16.551896 3.838266 18.187241 electrons x Angstroem
dipolmoment 16.532813 3.833460 18.186043 electrons x Angstroem
dipolmoment 16.570875 3.843147 18.194894 electrons x Angstroem
dipolmoment 16.548437 3.833974 18.192158 electrons x Angstroem
dipolmoment 16.555751 3.842717 18.189156 electrons x Angstroem
dipolmoment 16.549568 3.839086 18.174361 electrons x Angstroem
dipolmoment 16.554322 3.837544 18.206755 electrons x Angstroem
dipolmoment 16.543874 3.840816 18.195206 electrons x Angstroem
dipolmoment 16.559504 3.835846 18.186005 electrons x Angstroem
dipolmoment 16.552356 3.839836 18.191090 electrons x Angstroem
dipolmoment 16.551936 3.836908 18.190327 electrons x Angstroem
dipolmoment 16.554123 3.839745 18.192979 electrons x Angstroem
dipolmoment 16.550043 3.836981 18.188212 electrons x Angstroem

What I notice here is the first 3 steps are different with respect to each other. The latter gives me 1 jump (from 11.889 to 16.555 in the x-axis for example) then basically a very small changes afterwards, while the first one gives 2 jumps (from 10.93, to 15.21, to 20.37). Why is that?

Another thing that I notice as well: in the first three OUTCAR, the 'min pos' value differs. Where the first one gives me:
direction 1 min pos 57, direction 2 min pos 60, direction 3 min pos 59
direction 1 min pos 58, direction 2 min pos 61, direction 3 min pos 60,
direction 1 min pos 59, direction 2 min pos 61, direction 3 min pos 60,
and the rest will follow the 1 min pos 59, etc throughout.

and the second one gives me:
direction 1 min pos 58, direction 2 min pos 60, direction 3 min pos 59,
direction 1 min pos 59, direction 2 min pos 61, direction 3 min pos 59,
direction 1 min pos 59, direction 2 min pos 61, direction 3 min pos 59,

<span class='smallblacktext'>[ Edited ]</span>

[tanggara]

I figured it out!

The problem lies with the inadequacy of my KPOINTS (I used 4x4x4 and the problem goes away).
<span class='smallblacktext'>[ Edited Sun Jan 15 2012, 07:24PM ]</span>