[Pw_forum] magnetic anisotropy calculation using fully-relativistic PPs

[Peter Cybertron]

Hi,

I am working in University of Florida as a postdoc.
I am exploring the spin-orbital calculations using pwscf, and I 
encounter a very slow convergence like this:
 > grep estimated scf.out
      estimated scf accuracy    <       0.00000004 Ry
      ... (100 similar lines)
      estimated scf accuracy    <       0.00000003 Ry
 > grep "total energy" scf.out
     ...
      total energy              =   -3667.91077719 Ry
      total energy              =   -3667.91078176 Ry
      total energy              =   -3667.91077642 Ry
      total energy              =   -3667.91078300 Ry

Although the convergence of total energy seems OK (down to 0.00001 Ry ~ 
0.0001 eV = 0.1 meV), I still feel uncomfortable since I never encounter 
such a problem without spin-orbit interactions.

I downloaded the ultrasoft and PAW pseudopotentials from PSLib and I am 
using the PBE flavor of XC functional. The system I am studying is a two 
dimensional magnetic insulator.

The parameters I am using are:
  constrained_magnetization = 'total direction'
  fixed_magnetization(3) = 0.0
  lambda = 0.2
  ecutwfc = 30.0 ,
  ecutrho = 300.0 ,
  occupations = 'smearing' ,
  degauss = 0.005,
  smearing = 'mv' ,
  nosym=.true.
  mixing_mode = 'local-TF' ,
  mixing_beta = 0.9 ,
  diagonalization = 'david' ,

Which parameter on earth keep my calculations non-converged?

Best,
Yun-Peng