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

[Ghosh SUDDHASATTWA]

Dear Prof.Blaha, 
Thank you for the reply. The change in total energy by spin orbit coupling
is only by a few rydbergs, but it shows a huge change in kJ/mol. 
Thanks anyway. 
I will come back to the mailing list after I have incorporated "so" in fcc
zirconium. 
However, I still have the doubt. 
In case, we do the total energy calculation for the stable state (ground
state) with sp, and so both, 
Then for the lattice stability of the metastable state , do we have to do a
sp and so both. 
In the paper I referred to my earlier mail, sp has been done for Zirconium
which sounds strange. 
In your paper on hcp metals, you have not incorporated so for Zr. 
That means for lattice stability 
Ground state (sp, so) minus metastable state (sp,so) is right 
ground state (sp,so) minus metastable state (so) is wrong 

Am I right sir, 
Suddhasattwa 

-----Original Message-----
From: wien-bounces at zeus.theochem.tuwien.ac.at
[mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha
Sent: Sunday, June 13, 2010 9:40 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] FW: Differences in the hcp and fcc stabilities of
zirconium [Updated]

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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