[Pw_forum] Convergene of Magnetic moment is very slow

[ksaha at physics.udel.edu]

Dear Users,

I am running scf-iterations of a ferrimagnetic yttrium iron garnet (bcc
primitive cell with 80 atoms) system and find that the convergence of
magnetic moment is very slow. Can you any suggest me how to accelerate the
overall convergence? Please see the last a few steps of magmom of the
100-scf steps:

     total magnetization       =    78.61 Bohr mag/cell
     total magnetization       =    78.79 Bohr mag/cell
     total magnetization       =    78.78 Bohr mag/cell
     total magnetization       =    78.91 Bohr mag/cell
     total magnetization       =    79.25 Bohr mag/cell
     total magnetization       =    79.17 Bohr mag/cell
     total magnetization       =    79.22 Bohr mag/cell
     total magnetization       =    79.06 Bohr mag/cell
     total magnetization       =    79.08 Bohr mag/cell
     total magnetization       =    79.10 Bohr mag/cell
     total magnetization       =    79.12 Bohr mag/cell
     total magnetization       =    79.09 Bohr mag/cell
     total magnetization       =    79.15 Bohr mag/cell
     total magnetization       =    79.23 Bohr mag/cell
     total magnetization       =    79.17 Bohr mag/cell
     total magnetization       =    79.47 Bohr mag/cell
     total magnetization       =    79.45 Bohr mag/cell
     total magnetization       =    79.15 Bohr mag/cell
     total magnetization       =    81.33 Bohr mag/cell
     total magnetization       =    82.16 Bohr mag/cell
     total magnetization       =    82.24 Bohr mag/cell
     total magnetization       =    82.32 Bohr mag/cell
     total magnetization       =    82.53 Bohr mag/cell
     total magnetization       =    84.89 Bohr mag/cell
     total magnetization       =    82.93 Bohr mag/cell
     total magnetization       =    78.05 Bohr mag/cell
     total magnetization       =    84.82 Bohr mag/cell
     total magnetization       =    84.32 Bohr mag/cell
     total magnetization       =    84.69 Bohr mag/cell
     total magnetization       =    85.38 Bohr mag/cell
     total magnetization       =    87.34 Bohr mag/cell

Also, here is the part of the script which you may want to look at:

 &system
    ibrav = 3,
    celldm(1) = 23.24362966,          ! = a, in Bohr
    nat= 80,
    ntyp= 3,
    nspin=2,
    starting_magnetization(1)=0.0,
    starting_magnetization(2)=2.60,
    starting_magnetization(3)=0.0,
    occupations='smearing',
    smearing='mp',
    degauss=0.02,
    ecutwfc =30,
    ecutrho =240
 /
 &electrons
    electron_maxstep = 400,
    diagonalization='david',
    conv_thr = 1.0e-6,
    mixing_beta = 0.05,
    !mixing_ndim = 6
    mixing_ndim = 10
 /
ATOMIC_SPECIES
 Y   88.90585    Y.pbe-nsp-van.UPF
 Fe  55.84500    Fe.pbe-sp-van_mit.UPF
 O   15.99940    O.pbe-van_ak.UPF
.
.
.
K_POINTS automatic
 5 5 5  1 1 1

Many thanks for your comments and suggestions,

Regards,
Kamal

==========================================================
 Kamal K. Saha
 Department of Physics and Astronomy
 University of Delaware
 Newark, DE 19716-2570
 Phone: (302) 831-8519, Fax: (302) 831-1637

 http://web.physics.udel.edu/about/directory/postdoc/kamal-k-saha
==========================================================