[Wien] [SPAM?] RE: [Wien2k Users] Overlapping spheres error duringOptimize.job

[Rocquefelte]

Yes for sure, you should use more than 3% reduction of the RMTs if you 
plan to consider up to 10% variation of the c/a ratio.
However, I would first simply generate the two extrema structures and 
check the NN distances. Then you simply have to compare the NN distances 
variation from +10% to 0% to -10% and it will give you a better idea of 
what you are really doing and which RMT you should use (the smallest one).
Last but not the least, check that 10% variation do not induce too 
strong NN variations. In fact, I imagine that 5% variation should be 
sufficient to find the c/a equilibrium value.

Regards

Xavier


Ghosh SUDDHASATTWA a écrit :
>
> Dear Xavier,
>
> Thanks for the kind comments.
>
> I am trying to find the equilibrium c/a and not pressure effects.
>
> I have in fact used the RMT option in the structure generator (I had 
> used 3%).
>
>  
>
> May be I have to use more than 3%
>
> Am I right?
>
> Thanks again
>
>  
>
> SG
>
>  
>
>  
>
> ------------------------------------------------------------------------
>
> *From:* wien-bounces at zeus.theochem.tuwien.ac.at 
> [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] *On Behalf Of 
> *Rocquefelte
> *Sent:* Saturday, March 20, 2010 12:05 PM
> *To:* A Mailing list for WIEN2k users
> *Subject:* Re: [Wien] [Wien2k Users] Overlapping spheres error 
> duringOptimize.job
>
>  
>
> Dear Ghosh,
>
> The suggestion is already contained in your question.
> The choice of the RMT should be done with car in such situation.
> The best is simply to create the smallest structure and to estimate 
> the corresponding RMT.
> Then you will have no overlap problems.
>
> Another solution simply consists to use one option in the structure 
> generator (reduce RMT by X%).
>
> Concerning option 2, it really depends of what you want to do.
> Are you trying to reproduce pressure effects?
> Are you trying to find the equilibrium c/a ratio?
> ..
>
> Regards
>
> Xavier
>
>
> Ghosh SUDDHASATTWA a écrit :
>
> Dear Wien2k Users,
>
> I was trying to do a c/a optimization for hexagonal zirconium (well 
> studied system; example Blaha'a paper on hcp metals). I used Option 2 
> in the optimization and varied the c/a ratio from -20 to +20.
>
> The rkmax was 8.00 and RMT around 2.3
>
> There was an error "overlapping spheres"
>
>  
>
> Physically if we try to visualize this, when we try to compress the 
> c/a like -15 or -20%, the RMT would definitely overlap and it is 
> natural that the structure would not have the best equilibrium c/a. I 
> hope my arguments are right.
>
>  
>
> So, there are two options
>
> 1 Reduce RMT
>
> 2. Reduce -20 to +20 variation to -10 to +10
>
>  
>
> I chose 2; still got the same error.
>
> Any suggestions
>
> Suddhasattwa
>
>  
>
>
> ------------------------------------------------------------------------
>
>
>  
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