About local magnetization with VASP using RWIGS

[vietbac]

Dear Bader admin and users,

I have problem with analyzing local magnetization of ferromagnetic clusters by VASP. I found the Bader program and this forum are useful, getting RWIGS from Bader I could analyse local charge. But never I have got the right value for magnetic moments if I set RWIGS in the INCAR to get local magnetization at the end of OUTCAR.

My interested metallic clusters including several layers and the charge of centered atom differs from of surface atoms. So I set the RWIGS value like this

RWIGS = 1.7 12*1.5 #(ex 13 atom-cell)

I used PAW potentials and get RWIGS form MIN DIST of Baber.

I would appreciated any help and suggestion,
BRs,
vietbac

[graeme]

I don't think that using a value of RWIGS set to the minimum distance between the Bader surfaces at the atoms makes physical sense. The problem with the RWIGS based analysis in vasp is that the volumes around each atom are spheres. These spheres do not tile to fill space, so that the sum of local charge (or magnetism) will not give the total value. It is also not clear how to set RWIGS. The Bader analysis is all about finding a set of atomic volumes that uniquely partition the space around atoms.

[vietbac]

I don't think that using a value of RWIGS set to the minimum distance between the Bader surfaces at the atoms makes physical sense. The problem with the RWIGS based analysis in vasp is that the volumes around each atom are spheres. These spheres do not tile to fill space, so that the sum of local charge (or magnetism) will not give the total value. It is also not clear how to set RWIGS. The Bader analysis is all about finding a set of atomic volumes that uniquely partition the space around atoms.

Thank you for your reply and useful explanation,

I found another topic in this forum about spin distribution

by graeme on Sun Jun 03, 2007 1:35 am

You can only get core charges with the PAW potentials. Using the total charge density is important for accurate charges.

Yes, you can analyze the spin density in the same way as the charge density. It could make sense to use the total charge density to find the Bader volumes, and then add up the spin density in those volumes, using:

bader CHGCAR_spin -ref CHGCAR_total

As I understand with spin polarized calculation in VASP, CHGCAR will print out both the total charge density (up + down) and the spin density (up - down) and the magnetizaton is obtained from the differences of the spin up and down charges. So we can separate spin up and spin down charges.

So my question is what do CHGCAR_spin and CHGCAR_total mean?
Thank you,

[graeme]

CHGCAR_spin is the spin_up - spin_down. CHGCAR_total is the spin_up + spin_down, although you should include core charges in this file; see: http://http://theory.cm.utexas.edu/henk ... ode/bader/