[Pw_forum] convergence problem in scf calculation in rare earth oxide Sm2O3

[Ari P Seitsonen]

Dear Mohammed,

   I do not not know anything about the compound, but one note: Did you 
notice that the keyword 'starting_magnetization' expects values between -1 
and 1, those limits meaning full spin polarisation of the valence 
electrons (or, a relative polarisation)? If this is not what you wanted, 
the guess (ferro-magnetic, apparently) for the initial density can be 
quite far from the final value. And indeed all the lanthanides are 
difficult to handle, I do not know how accurate the available PAW/pseudo 
potentials are; one might consider starting initially with a fixed 
total magnetisation to see if one can converge then. Yet in some cases I 
am still fighting to get the electronic structure to converge, even in 
molecules.

   Sorry, I have no better suggestions.

     Greetings,

        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 Sat, 25 Nov 2017, Mohammed Khalafalla wrote:

> Dear all,
> I could not achieve scf convergence in Sm2La2O6 (the input file is attached herewith). This was the case even after several 'restart' of the
> calculation with different pseudpotentials specially for 'O' atom. I guess I used well tested PAW psedu for rare earth from
> http://www.vlab.msi.umn.edu/resources/repaw/index.shtml
> I used recommended hubbard potentials and spin polarization, but no change. Generally I found convergence in (Sm,O) system to be difficult. Can
> you kindly let me know which parameter set-up would determine successful convergence in (Sm,O) system?
> Regards,
> Mohammed A. H. Khalafalla (PhD)
> Taibah University
> KSA
> 
> 
>