About Zero magnetic moment in FePt

[Makhlouf Kharoubi]

Dear developers,

I'm calculating ordered L1_0 FePt using the latest (0.9.224) exciting version.
i included spin polarization and spin-orbit coupling in order to calculate the MOKE.

The convergence was reached easily, up to 0.00001, but the MOMENT.OUT showed a zero magnetic moment.

i reset muffin tin radii of iron to 2.3, and of Pt to 2.5 in Fe.in, and Pt.in in the species directory.

I increased the number of empty bands and BZ mesh.

I don't know what's wrong 

thank you in advance

This is the exciting.in used
!--------------------------------------------
tasks
0
10
20
120
122

! the relaxation time is taken to be 1/swidth
!swidth
! 0.01

spinpol
.true.

! spin-orbit coupling is required for MOKE
spinorb
.true.

bfieldc
0.0 0.0 0.01

nempty
30

avec
1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.387343444

scale
5.160810382

sppath
'../../species/'

atoms
2 : nspecies
'Fe.in' : spfname
1 : natoms
0.0 0.0 0.0 0.0 0.0 0.0 : atposl, bfcmt
'Pt.in' : spfname
1 : natoms
0.5 0.5 0.5 0.0 0.0 0.0 : atposl, bfcmt

ngridk
16 16 16

vkloff
0.5 0.5 0.5

[Bultmark]

Hi

Sometimes a faster convergence of the magnetic moment can be achieved by starting with a larger field, for example

bfieldc 
0.0 0.0 10.0

and then lower the field every iteration with the flag

reducebf
0.75

With this setup the applied field will be 10 the first iteration, 7.5 the second and so on. The high field in the first few iterations will force the magnetic moment to become large and then converge from above rather than from below. Usually the convergence from above is faster.

Happy computing

/fredrik bultmark

[Makhlouf Kharoubi]

Thanks to Frederik for his highlights,

by setting:
bfieldc
0.0 .0. 10.0
i get a total magnetic moment of:

-0.2783699990E-19  0.1301609909E-19  -2.867197277

but after setting
reducebf
0.75

tho total magnetic moment decrease every iteration until it became very small:
here bellow, the MOMENT.OUT file for SCF cycle:

-0.2783699990E-19  0.1301609909E-19  -2.867197277
  0.1251810919E-18  0.3988457821E-19  -1.668360767
  0.6191338539E-19 -0.5615394444E-20  -1.379373978
  0.7347896801E-20  0.2443680691E-19  -1.084004127
-0.2580657003E-19  0.1607170329E-19 -0.9349549288
-0.4814645244E-19  0.2245462263E-19 -0.7872795972
-0.1366248740E-19  0.1656533472E-19 -0.6528726141
-0.9495394031E-20  0.5818447949E-20 -0.5312738989
  0.1067300969E-19 -0.4366662723E-20 -0.4234078898

NB:
i used a large k-mesh:
ngridk
36 36 36

and a more empty states:
nempty
10

So how can i maintain the total magnetic moment in this case?

many thanks