[Pw_forum] Nscf with large number of bands for GW

[Thierry Clette]

Hello,

I want to do some nscf calculations in order to compute GW corrections 
afterwards. I know that I need a lot of bands to converge, around 3000 
(I already did some convergence studies in another code).
A example of an input is attached.
This seems to be a problem for the code, as when I go higher than about 
500 bands, I get the ¨error computing cholesky¨, which means the 
diagonalization fails.

I read a lot of different topics in the mailing list reporting this 
problem, with various solutions such as :
- parallelization on bands
- CG diagonalization
- bigger ¨diago_thr_init¨ (even if I need to be quite precise in the end)
- beginning from a previous calculation with ~500 bands.

I tried different things and it still didn't work. BTW, I know the 
calculation is possible, because I did it without problems in Abinit 
with the same parameters (Abinit seems to work differently).

At this stage, I really don't know what I should do. Has someone already 
done successful calculations with so many bands ?

Thanks in advance,

Thierry Clette



-------------- next part --------------
&control
  calculation = 'nscf'
  wf_collect= .true.
  prefix = 'MoS2',
  pseudo_dir='./'
  /
 &system
  ibrav = 4, celldm(1) = 6.0185614822E+00, celldm(3) = 6.6461, nat = 3, ntyp = 2,
!relax abinit nso, 40/a
  ecutwfc = 76,
  nbnd=2000,
  occupations = 'smearing', smearing = 'gaussian', degauss = 0.001,
  nspin = 1,
  nosym = .false.
  force_symmorphic= .true.
 /
 &electrons
  diago_full_acc = .true.
  diago_thr_init = 1.0e-10
!conv sur les eigenvalues
!conv_thr = 1.0d-10, foireux
 /
ATOMIC_SPECIES
Mo  95.96  Mo.upf
S   32.06  S.upf
ATOMIC_POSITIONS (bohr)
Mo       1.7763568394E-15  3.4748180920E+00  8.7435638920E-20
S        3.0092807411E+00  1.7374090460E+00  2.9537981569E+00
S        3.0092807411E+00  1.7374090460E+00 -2.9537981569E+00
K_POINTS AUTOMATIC
9 9 1 0 0 0