[Pw_forum] Cannot achieve SCF convergence when attempting to relax bulk MoS2

[Ari P Seitsonen]

Dear Dan,

   Bulk? If I see correctly, the axis between the supposed-layers is 5.972 
Bohr * 24.472 = HUGE. I would recommend you to check the value of 
'celldm(3)' for the beginning.

   I also suggest to use 'a' and 'c' instead of celldm({1,3}) if you want 
to work in Ångströms.

     Greetings from Montrouge,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Ecole Normale Supérieure (ENS), Département de Chimie, Paris
   Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 15 Jan 2015, Dan Rubin wrote:

> I am just starting to use this software so i have undoubtedly made a simple
> mistake, however I cannot seem to get SCF convergence after 100 itterations.
> Here is the input file I am using:
> 
> &CONTROL
> title = MoS2_relax ,
> calculation = 'relax' ,
> wf_collect = .true. ,
> outdir = '/home/users/drubin/MoS2/temp/' ,
> wfcdir = '/home/users/drubin/MoS2/cpu_temp/' ,
> pseudo_dir = '/home/users/drubin/MoS2/pseudo/' ,
> prefix = 'MoS2_relax' ,
> verbosity = 'high' ,
> tprnfor = .true. ,
> /
> &SYSTEM
> ibrav = 4,
> celldm(1) = 5.972,
> celldm(3) = 24.472,
> nat = 6,
> ntyp = 2,
> ecutwfc = 48 ,
> ecutrho = 407 ,
> exxdiv_treatment = 'gygi-baldereschi' ,
> /
> &ELECTRONS
> diagonalization = 'david' ,
> diago_david_ndim = 8,
> /
> &IONS
> /
> ATOMIC_SPECIES
> Mo 95.96000 Mo.pbe-spn-kjpaw_psl.0.2.UPF
> S 32.06600 S.pbe-n-kjpaw_psl.0.1.UPF
> ATOMIC_POSITIONS crystal
> Mo 0.333333300 0.666666700 0.250000000
> Mo 0.666666700 0.333333333 0.750000000
> S 0.666666700 0.333333333 0.121000000
> S 0.333333333 0.666666700 0.878999999
> S 0.333333333 0.666666700 0.620999990
> S 0.666666700 0.333333333 0.379000000
> K_POINTS automatic
> 3 3 3 1 1 1
> 
> 
> Any help is greatly appreciated. 
> 
> Dan R.
> 
>