[QE-users] convergence NOT achieved after 100 iterations for spin-orbit coupling

[Kazume NISHIDATE]

Hi, Ream: 

You should use smal value for the mixed_beta.
Attached is the example of the input file of your system which reached
to the first scf state at the 50 iterations.
========
    convergence has been achieved in  50 iterations
     Entering Dynamics:    iteration =     1
========
This calculation was made by the NEC's LS parallel computer at the
TOHOKU university.

Note that I omitted the nspin=4 flag. It is not the the default flag
in the noncollinear calculation.

Here is the QE manual page on the issue of 'nspin=4' setting:
 > nspin = 4 :  spin-polarized calculation, noncollinear
 >              (magnetization in generic direction)
 >              DO NOT specify nspin in this case; specify 
 >              noncolin=.TRUE. instead

Also see the line 1 of the page.4 of the following PDF file.
It stated that:
 > - nspin:- the noncolin and nspin are conflicting flags, both should
 >   not be present within the same calculation


I do not know the correctness of the above statement, but you should
try this first.

I show you only the first part of the input file since the
other is the same of your input file. I can not describe the modifications, 
but these meaning may be clear following the manual.

========
&CONTROL
     calculation = 'relax' ,
     restart_mode = 'from_scratch' ,
     pseudo_dir = '../pseudo' ,
     outdir = './work',
     prefix= 'gr-sc-n',
     tstress = .true. ,
     tprnfor = .true. ,
     forc_conv_thr = 1.00e-03,
      wf_collect=.true.,
      nstep = 200,
/
&SYSTEM
                       ibrav = 0,
                   celldm(1) = 27.89615,
                         nat = 66,
                        ntyp = 3,
                     starting_magnetization(1)= 0.5,
                     noncolin= .true. ,
                     lspinorb= .true. ,
                     ecutwfc = 60.0 ,
                     ecutrho = 600.0 ,
                        nbnd = 280,
                 occupations = 'smearing' ,
                     degauss = 0.02,
                    smearing = 'gaussian' ,
/
&ELECTRONS
                    conv_thr = 5.0e-8 ,
                 mixing_mode = 'plain' ,
                 mixing_beta = 0.25,

/
==============


best regards
kazume NISHIDATE
敬具　西館数芽

nisidate at iwate-u.ac.jp
kazume.nishidate at gmail.com