[Wien] optimization

[Rocquefelte]

Dear Hazem,

When you are doing spin-polarized calculations, it consists to :
- treat correctly the spin state of the magnetic atoms (change in the 
total energy up to few eV/f.u.)
- treat the long-range magnetic order (change in the total energy by 
less than 1eV usually - 100 meV ...)

The effect of the long-range order on the atomic structure is 
negligible. However, the effect of the correct treatment of the spin 
state (high spin, low spin) of the magnetic atom could be very strong, 
depending of the nature of the states involved (bonding or antibonding 
levels).

Then, usually the less expensive strategy consists to optimize the 
structure using a spin-polarized calculation based on a ferromagnetic 
order (no symmetry lowering).
The total energy of other magnetic orderings could then be deduced using 
the optimized structure of the ferromagnetic order.

Regards

Xavier Rocquefelte
 
hazem salem a écrit :
> Dear all,
>             I have a question about optimizing the lattice constant. 
> If the system is magnetic is it necessary to use spin-polarized 
> calculations for optimizing the lattice constat, or one can do this 
> with a non-spin polarized calculations then use the optimum lattice 
> constant to perform spin-polarized calculations?
>  
> Thanks in advance
> Hazem
>
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