[QE-users] C anion SCF convergence

[Aulia Sukma Hutama]

Dear All,


I am unable to achieve SCF convergence of simple C- anion in its quartet
ground state. It appears there is an energy oscillation from the output
file so I terminated the calculation. I have tried to change the
mixing_beta value, mixing_mode, starting_magnetization value but there
seems no improvement on the results. Does anyone have any idea how to solve
this problem or did I make a mistake when trying to calculate anion?

Below are my input files for this calculation and the few last lines of the
output.

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

&CONTROL
  calculation = "scf",
  pseudo_dir  = "/media/metal/Work/qe_pseudo",
  prefix      = "C"
/
&SYSTEM
  ibrav       = 0,
  nat         = 1,
  ntyp        = 1,
  ecutwfc     = 45.0,
  ecutrho     = 400.0,
  nspin = 2,
  tot_charge = -1
  starting_magnetization(1)=1.0
  tot_magnetization = 3.0
  starting_charge(1) = -1
/
&ELECTRONS
  conv_thr    = 1.D-6,
/
CELL_PARAMETERS angstrom
20.0  0.0  0.0
 0.0 20.0  0.0
 0.0  0.0 20.0
ATOMIC_SPECIES
C  1.0  C.pbesol-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS crystal
C     0.500000000         0.5000000         0.5000000
K_POINTS gamma

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

    iteration # 55     ecut=    45.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     c_bands:  1 eigenvalues not converged
     ethr =  2.60E-06,  avg # of iterations = 10.5

     total cpu time spent up to now is      758.7 secs

     total energy              =     -17.72466906 Ry
     Harris-Foulkes estimate   =     -17.72579866 Ry
     estimated scf accuracy    <       0.85267583 Ry

     total magnetization       =     3.00 Bohr mag/cell
     absolute magnetization    =     3.00 Bohr mag/cell

     iteration # 56     ecut=    45.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     c_bands:  1 eigenvalues not converged
     ethr =  2.60E-06,  avg # of iterations = 11.5

     total cpu time spent up to now is      773.3 secs

     total energy              =     -17.70913541 Ry
     Harris-Foulkes estimate   =     -17.72533527 Ry
     estimated scf accuracy    <       1.03751336 Ry

     total magnetization       =     3.00 Bohr mag/cell
     absolute magnetization    =     3.00 Bohr mag/cell

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

Aulia Sukma Hutama
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