[Wien] please help

[Peter Blaha]

I'm not surprised that a Gd-supercell does NOT converge in an 
unpolarized calculation.

You have to consider the underlying physics: Gd metal has 7 4f 
electrons, thus in a polarized calculation this gives a rather stable 
situation, i.e. "all" 7 spin-up states are occupied, but all 7 spin-dn 
states empty.
In an unpolarized case you must put 7 electrons into "3.5 states" (each 
state takes now 2 electrons!) and it is rather naturally that this will 
cause problems.

The VERY efficient mixer seems to manage this for pure Gd, but in the 
supercell there are many more degrees of freedom and thus convergence is 
much more difficult. Eventually, switching to TEMP and a rather large 
broadening will help to converge.

In any case, you have to ask yourself: what should this calculation be 
good for ?? Even above the Neel/Curie-point one has local magnetic 
moments (only the long range order has gone).

susanta mohanta schrieb:
> 
> Dear all,
>              
> I have finished spin polarised calculation for Gd(2*2*2 supercell) with Cd
> impurity.But When I started with same structure for unpolarised calculation
> with RKMAX=7.5:GMAX=14 and 300kpoints(to begin with),the computation
> doesn;t seems to converge.After 200 cycle we noticed that both charge and
> energy are oscillating.So please help me in this regard.I have also 
> calculated
> unpolarised calculation for pure Gd.So what may be the problem?
>  
> with regards
> susanta
> 
> -- 
> SUSANTA K MOHANTA
> RESEARCH SCHOLAR
> DEPT.OF PHYSICS
> IIT KHARAGPUR
> *****************************
> 
> 
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