[QE-users] Problem with SCF including spin-orbit coupling

[pboulet]

Dear All,

I have some troubles with a SCF calculation using SOC (QE 6.1).
I have optimised a structure with non-SOC pseudopotentials and now I want to perform a SCF calculation by including SOC to get the electronic band structure. The problem is that the SCF diverges right away as you can see here:
>>>>
Self-consistent Calculation

     iteration #  1     ecut=    35.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  1.00E-05,  avg # of iterations = 14.2

     negative rho (up, down):  8.197E+02 0.000E+00

     total cpu time spent up to now is     2293.7 secs

     total energy              =  -16093.90449193 Ry
     Harris-Foulkes estimate   =  -18277.15379034 Ry
     estimated scf accuracy    < 5077678.52441197 Ry

     iteration #  2     ecut=    35.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  1.00E-02,  avg # of iterations =  5.0

     negative rho (up, down):  2.677E+03 0.000E+00

     total cpu time spent up to now is     3119.6 secs

     total energy              =   79024.56634461 Ry
     Harris-Foulkes estimate   =  -17101.52000727 Ry
     estimated scf accuracy    < 4036754.22296032 Ry

     iteration #  3     ecut=    35.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  1.00E-02,  avg # of iterations =  6.0

     negative rho (up, down):  2.815E+03 0.000E+00

     total cpu time spent up to now is     4658.4 secs

     total energy              =  132135.46722241 Ry
     Harris-Foulkes estimate   = -142275.32127673 Ry
     estimated scf accuracy    < 6116470.38137350 Ry
<<<<<
 
I am using PAW pseudopotentials (Ba, Rh, Ge and S) from the PSL library.  The cg diagonalisation does not solve the problem. 

Here is a piece of the input file:
&CONTROL
  calculation   ='nscf',
  nstep         = 300,
  etot_conv_thr = 1.d-7,
  forc_conv_thr = 1.d-4,
  wfcdir        = './WFC' ,
  prefix        = 'STe_nscf_LS',
  pseudo_dir    = '/scratch/cnt0022/pmc6881/paboulet/pseudo/',
  verbosity     = 'high',
  restart_mode  = 'restart',
  wf_collect    = .true.,
  disk_io       = 'high',
/
&SYSTEM
!  celldm(1)   = 1.0,
  nat         = 52,
  ntyp        = 5,
  ibrav       = 0,
  ecutwfc     = 35.d0,
  ecutrho     = 350.d0,
  occupations = 'fixed',
  nbnd        = 630,
  lspinorb    = .true.,
  noncolin    = .true.,
  nr1 = 72, nr2 = 72, nr3 = 360,
/
&ELECTRONS
  electron_maxstep = 200,
  conv_thr         = 1.d-10,
  mixing_beta      = 0.2d0,
  diagonalization  = 'david',
/

K_POINTS automatic
16 16 8 0 0 0

ATOMIC_SPECIES
Ba 137.3270   Ba.rel-pbe-spn-kjpaw_psl.1.0.0.UPF,
Rh 102.9055   Rh.rel-pbe-spn-kjpaw_psl.1.0.0.UPF,
Ge  72.6400   Ge.rel-pbe-dn-kjpaw_psl.1.0.0.UPF,
S   32.0650   S.rel-pbe-nl-kjpaw_psl.1.0.0.UPF,
Te 127.6000   Te.rel-pbe-dn-kjpaw_psl.0.2.2.UPF

etc…


Do you have a special recipe for this type of calculation?

Thank you,
Best regards

Pascal Boulet
—
Professor in computational materials - DEPARTMENT OF CHEMISTRY
Aix-Marseille University - Avenue Escadrille Normandie Niemen - F-13013 Marseille - FRANCE
Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50
Email : pascal.boulet at univ-amu.fr <mailto:pascal.boulet at univ-amu.fr>







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