[QE-users] magnetic moment and absolute magnetization

[Ing. Martin Matas]

Dear Pooja,

The list of atomic charges and magnetizations takes into account the values from the spheres around the ions which do not fill the entire space. However, the values of total and absolute magnetization are integrals over the whole simulation cell.
In your sparse cell (6.09 Å lattice constant for fcc metal), this difference may be substantial and may lead to such low charges and magnetizations inside the atomic spheres.

Martin Matas
PhD graduate
University of West Bohemia
Czech Republic


 Středa, Červen 26, 2024 13:43 CEST, Pooja Vyas <poojavyas at mkbhavuni.edu.in> napsal:

> My input script is as follows:
> 
> &CONTROL
>   calculation = 'scf'
>   prefix = 'v3al'
>   outdir = './'
>   pseudo_dir = './'
>   tprnfor = .true.
>   tstress = .true.
>   verbosity = 'high'
> /
> 
> &SYSTEM
>   ibrav = 2
>   celldm(1) = 11.512210722
> !  space_group = 225
>   nat = 4
>   ntyp = 4
>   ecutwfc = 60
>   ecutrho = 400
>   occupations = 'smearing'
>   smearing = 'cold'
>   degauss = 0.005
>   nspin = 2
>   starting_magnetization(1)=0.0
>   starting_magnetization(2)=0.0
>   starting_magnetization(3)=0.3
>   starting_magnetization(4)=-0.3
> /
> 
> &ELECTRONS
> /
> 
> ATOMIC_SPECIES
> Al 26.9815 Al.pbe-n-van.UPF
> V1 50.9415 V.pbe-n-van.UPF
> V2 50.9415 V.pbe-n-van.UPF
> V3 50.9415 V.pbe-n-van.UPF
> 
> ATOMIC_POSITIONS (crystal)
> Al            0.0000000000       -0.0000000000       -0.0000000000
> V1            0.5000000000        0.5000000000        0.5000000000
> V2            0.2500000000        0.2500000000        0.2500000000
> V3            0.7500000000        0.7500000000        0.7500000000
> 
> 
> K_POINTS automatic
>   20 20 20 0 0 0
> -------------------------------------
> The magnetic moment per site is:
>      atom   1 (R=0.179)  charge=  1.5425  magn= -0.0000
>      atom   2 (R=0.179)  charge=  3.4200  magn=  0.0003
>      atom   3 (R=0.179)  charge=  3.3857  magn=  1.3175
>      atom   4 (R=0.179)  charge=  3.3853  magn= -1.3178
> 
> and      total magnetization       =    -0.00 Bohr mag/cell
>             absolute magnetization    =     3.43 Bohr mag/cell
> 
> The sum of the individual magnetic moment does not give the value equal to
> that of absolute magnetization. Also the reported values of moments are
> 1.75 and -1.75. Why is there a difference between sum of moments and
> absolute value? and why are the moments low?