[Wien] [Wien2k Users] Lattice Stability using Structure Optimization

[Ghosh SUDDHASATTWA]

Dear Martin, 
Probably I am responding to your mail after a long time. And moreover, you
are absolutely correct. 
If Pu is imagined to be in the Zr atomic positions, it is very natural that
the occupation of Pu would naturally increase the c/a ratio  and there is no
meaning to do a structure optimization for cases like -2 % or -5 % change in
c/a ratio. The equilibrium c/a would be somewhere around +12-15 % change
(gross)  and this is what is expected from physics. 
That is what I get from Wien2k 

Thanks Stefaan and Martin, 

Suddhasattwa Ghosh 


-----Original Message-----
From: wien-bounces at zeus.theochem.tuwien.ac.at
[mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Martin Pieper
Sent: Tuesday, March 02, 2010 6:32 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] [Wien2k Users] Lattice Stability using
StructureOptimization

Dear Ghosh Suddhasattwa,

being a beginner with Wien2k myself and not having read your exchange with 
Stefaan I probably should be quiet to avoid confusion but maybe its simple: 
Did you adapt (enlargen) the lattice constant when you put in Pu instead of 
Zr? I would expect that Pu needs a lot more space than Zr and, therefore,
you 
might simply be too far away from any reasonable lattice constant and far
out 
of the trial range of the optimization procedure...

Best regards,

Martin


Am Montag, 8. März 2010 schrieb Ghosh SUDDHASATTWA:
> Dear Dr.Stefaan,
>
> Coming back to the problem we discussed regarding lattice stability a few
> days back, I have done a few things but am not able to proceed further.
>
> I imagine Pu in a Zr lattice (hcp, space group 194)
>
> There is only one equivalent position (0.3333333 0.666667 0.25)
>
> I replaced Zr atom with the Pu atom.
>
> My approach was the following
>
> 1.	Calculate ENE without spin orbit and with spin orbit
> 2.	Structure optimization (Option 5)
>
>
>
> The ENE without spin orbit was -118767.962 Ry and with spin orbit was
> -118769.097 Ry.
>
> I chose Option 5 for the structure optimization and it created 16
different
> struct files.
>
> Optimize.job was run and it did not give any errors. (Removed # from x
> dstart only)
>
> When I chose energy vs volume in plot; it gave a linear variation and not
> like what is given in the UG guide for TiC.
>
> Can you please tell me if I have done any mistake?
>
>
>
> Suddhasattwa Ghosh



-- 
Dr. Martin W. Pieper
Institut f. Physik, 
Karl-Franzens Universität Graz
Universitätsplatz 5, 
A - 8010 Graz, AUSTRIA
Tel.: +43-316-380-8564, Fax: +43-316-380-9816,
email: martin.pieper at ifp.tuwien.ac.at
_______________________________________________
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien