[Wien] FW: Differences in the hcp and fcc stabilities of zirconium [Updated]

[Peter Blaha]

You cannot compare total energies of calculations with and without SO.

Ghosh SUDDHASATTWA schrieb:
>  
> 
> Dear Wien2k users,
> 
> Initially, I did the total energy calculation of hcp Zirconium with c/a 
> optimization.
> 
> I had updated the command in the optimize.job
> 
> Run_lapw –cc 0.0001 –ec 0.0001 –so
> 
>  
> 
> I got a fairly good plot of energy vs c/a. The equilibrium energy with 
> optimized c/a was -7198.44622432 Ry/atom
> 
> I did the same job for fcc zirconium (metastable state)
> 
> I did the volume optimization with the command in the optimize.job
> 
> Run_lapw –cc 0.0001 –ec 0.0001
> 
> Without spin orbit coupling
> 
> The equilibrium energy was -7198.427610 Ry/atom
> 
> If we take the difference, it comes out to be -0.01861432 Ry/atom.
> 
> If we convert to kJ/mol, it comes out to be -24.435 kJ/mol (multiply 
> Ry/atom by 13.6 eV and 96.48846 kJ/mol)
> 
>  
> 
> The difference seems to be very large. The difference is reported to be* 
> -3.69 kJ/mol *by VASP. (PAW-GGA) {CALPHAD, 28 (2004) 78-90}
> 
> Can anybody tell me as to why I am getting such a high value of the 
> lattice stability?
> 
> Is it because of the incorporation of spin orbit coupling?
> 
> I had initially used the in1new switch to get the best linearization 
> energies for both the cases, still I am getting such a high value
> 
> Any suggestions?
> 
>  
> 
> Suddhasattwa
> 
>  
> 
>  
> 
>  
> 
> 
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-- 
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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