[Pw_forum] Non-collinear calculations: magnetic moment relaxation

[Lukashev Pavel]

Dear All,

I am running a test calculation of bcc iron, to check if the relaxation of
angle1 (theta) works correct for the non-collinear case. I have copied the
file "fe.pen.in" from the examples provided on pwscf.org, and added one more
Fe atom (so, I have two Fe atom unit cell). I set angle1(1)=90;
 angle1(2)=0.0. After self-consistent calculation I expect these angles to
be aligned (ferromagnetically). Yet, I end up getting very strange result,
i.e. theta(1)=70.356498; theta(2)=19.684944. Does this mean that the
relaxation of atomic magnetic moments is not very reliable in case of
non-collinear calculation? This is first time I am trying to include
non-collinearity in my calculation, therefore I don't have much to compare
with. And I did not find any published work on non-collinear systems done
with PWSCF. Any help on this issue is very appreciated. I attach my input
file which also includes portion from output showing magnetization
magnitude/direction.

Sincerely,

Pavel Lukashev, Ph.D.
Research Associate
UNL, Department of Physics & Astronomy
208 Theodore Jorgensen Hall
855 N. 16th Street
Lincoln, NE 68588-0299
Office: (402) 472-2400
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 &control
    calculation='scf'
    restart_mode='from_scratch',
    pseudo_dir = '/home/pavel/QE-4.2/espresso-4.2/pseudo/',
    outdir='/home/pavel/QE-4.2/espresso-4.2/examples/example13/results/TEST/tmp/',
    prefix='fe'
 /
 &system
    ibrav = 1, celldm(1) =5.217, nat= 2, ntyp= 2,
    ecutwfc = 25.0,ecutrho = 200.0,
    report=1,
    occupations='smearing', smearing='marzari-vanderbilt', degauss=0.05
    noncolin = .true.
    starting_magnetization(1) = 2.0
    starting_magnetization(2) = 2.0
    angle1(1)=90.0
    angle2(1)=0.0
    angle1(2)=0.0
    angle2(2)=0.0
    lambda = 1
 /
 &electrons
    conv_thr = 1.0e-8
    mixing_beta = 0.2
 /
ATOMIC_SPECIES
 Fe1 55.847 Fe.pz-nd-rrkjus.UPF
 Fe2 55.847 Fe.pz-nd-rrkjus.UPF
ATOMIC_POSITIONS
 Fe1 0.0 0.0 0.0
 Fe2 0.5 0.5 0.5
K_POINTS
 11
   0.0625000  0.0625000  0.0625000   1.00
   0.0625000  0.0625000  0.1875000   3.00
   0.0625000  0.0625000  0.3125000   3.00
   0.0625000  0.0625000  0.4375000   3.00
   0.0625000  0.0625000  0.5625000   3.00
   0.0625000  0.0625000  0.6875000   3.00
   0.0625000  0.0625000  0.8125000   3.00
   0.0625000  0.0625000  0.9375000   3.00
   0.0625000  0.1875000  0.1875000   3.00
   0.0625000  0.1875000  0.3125000   6.00
   0.0625000  0.1875000  0.4375000   6.00

===========================================================

OUTPUT:

     atom number    1 relative position :    0.0000   0.0000   0.0000
     charge :     6.428337
     magnetization :          2.269152    0.000000    0.809951
     magnetization/charge:    0.352992    0.000000    0.125997
     polar coord.: r, theta, phi [deg] :     2.409372   70.356498    0.000000

 ==============================================================================

 ==============================================================================
     atom number    2 relative position :    0.5000   0.5000   0.5000
     charge :     6.428357
     magnetization :          0.811645    0.000000    2.268714
     magnetization/charge:    0.126260    0.000000    0.352923
     polar coord.: r, theta, phi [deg] :     2.409529   19.684944    0.000000