magnetic moment

Message

Gilles · #1 Post by **Gilles** » Mon Sep 19, 2005 8:45 am

Dear all,

Where do I read the magnetic moment for a given system ?

Below an example (a Ti ad_atom on graphene 32 C atoms; ISPIN = 2 spin polarized ; PAW ; GGA 91).

*In the OSZICAR file, a keyword "mag" exists which gives "mag= 3.5150

*In the OUTCAR, at the end, a so-called "magnetization (x) " table is written, with the s, p, d and total components for each ion.
The total number is " 2.542". WHAT IS IT ?

THE question : Where can we read the magnetization value for a vasp job ?

Thank you for your help. ;-)

-------------------------
OSZICAR file
N E dE d eps ncg rms rms(c)
DAV: 1 -.299010549136E+03 -.29901E+03 -.36815E+00 9380 .134E-01 .621E-02
RMM: 2 -.299012305935E+03 -.17568E-02 -.20091E-02 7312 .434E-02 .855E-02
RMM: 3 -.299012486628E+03 -.18069E-03 -.16142E-03 7544 .180E-02 .222E-02
RMM: 4 -.299012510079E+03 -.23451E-04 -.46454E-04 7385 .215E-02
1 F= -.29901251E+03 E0= -.29901251E+03 d E = .000000E+00 mag= 3.5150

---------------
OUTCAR file

magnetization (x)

# of ion s p d tot
----------------------------------------
1 .000 .012 .000 .012
2 .000 .012 .000 .013
3 .001 .001 .000 .002
4 .000 .006 .000 .007
5 .001 .000 .000 .001
6 .000 .005 .000 .005
7 .000 .007 .000 .007
8 .000 .002 .000 .002
9 .000 .004 .000 .004
10 .000 .003 .000 .003
11 .000 .001 .000 .001
12 .001 .008 .000 .009
13 .000 -.001 .000 -.001
14 .001 .015 .000 .015
15 .000 .002 .000 .002
16 .000 .007 .000 .007
17 .000 .002 .000 .002
18 .000 .002 .000 .002
19 .000 .006 .000 .007
20 .001 .002 .000 .002
21 .001 .014 .000 .015
22 .000 -.001 .000 -.001
23 .001 .010 .000 .011
24 .001 .013 .000 .014
25 .000 .001 .000 .001
26 .000 .001 .000 .001
27 .001 .008 .000 .009
28 .000 .001 .000 .001
29 .000 .005 .000 .005
30 .001 .001 .000 .001
31 .001 .013 .000 .014
32 .001 .010 .000 .011
33 .218 .034 2.105 2.357
------------------------------------------------
tot .227 .209 2.105 2.542

BZINTS: Fermi energy: -2.028574;132.000000 electrons
Band energy:***********; BLOECHL correction: -.008199

#2 Post by **admin** » Wed Sep 21, 2005 3:07 pm

The difference of the magnetic moments as given in OUTCAR and
OSZICAR are due to the following reason:
1) in the last line of OSZICAR, the total magnetisation of the unit
cell (as defined by the Bravais matrix in POSCAR) is given
2) in the 'tot' line of OUTCAR, the sum of the LOCAL magnetic
moments is given. These local moments are obtained by
taking the difference of spin up and down charge in the
'spheres' defined by RWIGS (either from POTCAR or from
INCAR), centered at the atoms' positions. The sum of these
spheres usually is smaller than the total volume of the unit cell.
The difference thus corresponds to the contributions of the
'interstitial' region between the spheres.

hyon-jee · #3 Post by **hyon-jee** » Thu Jan 12, 2006 6:12 pm

Then should one change RWIGS to match the sum of those to the total volume of the unit cell?

tjf · #4 Post by **tjf** » Fri Jan 13, 2006 12:47 am

Yeah, but you never can in a rigorous way. Spheres aren't space-filling. Even if the volume of the spheres are equal to the volume of the unit cell, some regions will be double (or more) counted and some regions will be ignored. If you make the RWIGS so large as to cover all space there will be huge overlaps between the spheres and multiple counting of the magnetisation. The same applies to all RWIGS-based analysis, AFAIK.

jlrch · #5 Post by **jlrch** » Thu Feb 02, 2006 10:14 am

According to my experience, for d-orbitals (like in Ti) the analysis of the magnetic moments in the Wigner-Seitz sphere using the same RWIGS value as in the PAW potential file (POTCAR) seems quite appropriate. However, for s- and p-orbitals it would be better to use the Bader scheme as Graeme Henkelman (a member of this forum) pointed out in one of his messages.

VietBac · #6 Post by **VietBac** » Mon Jun 23, 2008 12:55 pm

Dear Vasp_users,
I would like to continue this thread by my question about RWIGS, which will make OUTCAR print the local charge and local moments at the end.
I always got the incompatible value between the total charge and total magnetization, i.e. with the appropiate RWIGS, the total charge is the same with the number of the valence electrons in my system but the total magnetization is not like the value in OSZICAR, can I trust in this local magnetic moments.
Thank you,

#7 Post by **admin** » Mon Jun 23, 2008 2:37 pm

please check the forum, this issue has been discussed over and over