Calculation of non-collinear $\alpha-Fe$.

Here is the Input file:

&control
    calculation = 'scf'
    restart_mode='from_scratch'
    prefix = 'fe'
    outdir = './outdir'
    pseudo_dir = '/BIGDATA1/ac_iphy_jrsun_1/soft/QE/SSSP'
    ! pseudo_dir = '/home/anonymous/quantumEspresso_2019/SSSP_precision_pseudos'
/
&system
    ibrav=3, celldm(1) =5.095843399, 
    nat=1, ntyp=1,
    ecutwfc=40
    ecutrho=320
    occupations='smearing',smearing='marzari-vanderbilt',degauss=0.01
    noncolin = .true.
    starting_magnetization(1) = 0.1
    angle1(1) = 90.0
    angle2(1) = 0.0 
    ! Here the spin is along x direction, but in cubic system, x =y =z;
/
&electrons
    conv_thr=1e-8
    mixing_beta = 0.3
/
ATOMIC_SPECIES
 Fe  55.845  Fe.pbe-spn-kjpaw_psl.0.2.1.UPF
ATOMIC_POSITIONS (alat)
 Fe 0.00 0.00 0.00
K_POINTS (automatic)
  10 10 10 0 0 0

New Tags:

1. noncolin = .true.: no need to set nspin
2. angle1(1): the angle with respect to z-axis
3. angle2(1): the angle between the project spin in xy-plane and the x-axis
4. mixing_beta: decrease mixing_beta can increase the convergence, however slower.

Also, we use the pw.x. (This is different with VASP.)

Below is part of output file:

    total magnetization       =     1.93     0.00     0.00 Bohr mag/cell
    absolute magnetization    =     2.01 Bohr mag/cell

    iteration # 10     ecut=    40.00 Ry     beta= 0.30
    Davidson diagonalization with overlap
    ethr =  4.86E-10,  avg # of iterations =  2.0

==============================================================================
    atom number    1 relative position :    0.0000   0.0000   0.0000
    charge :    14.301163
    magnetization :          1.953124   -0.000000    0.000000
    magnetization/charge:    0.136571   -0.000000    0.000000
    polar coord.: r, theta, phi [deg] :     1.953124   90.000000    0.000000

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