[Wien] c/a optimization

[shamik chakrabarti]

Dear Peter Blaha Sir,

                               should we change the indices in case.in0 to 0
0 0 and run the *c/a optimization again? *or after changing the indices what
command we should give?

Sir what is the meaning of *ifft parameters?*
*
*
*Sir actually we are giving an input structure having a c/a ratio 1.25

and expecting to get a ratio of 3.75. This thing we are doing because we are
giving an known structure as input and want to find the structure of a new
material. This material is formed due to the replacement of one atom in
A2BCO4 structure (c atom) by another atom say D and there is a material
ABDO4 having c/a ratio 3.75.......although it is quite possible that ABDO4
and A2BDO4 have different c/a ratio....our aim is only to obtained stable
c/a ratio for A2BDO4 structure.
*

*

*with best regards,

On Sat, Jul 10, 2010 at 4:27 PM, Peter Blaha
<pblaha at theochem.tuwien.ac.at>wrote:

> Change the indices in case.in0  to eg. 0  0  0   (this will recalculate
> the required ifft parameters).
>
> However: Please THINK what you are doing ???
> What is the meaning of changing c/a by factors of 3,4,5 .... ???
> Usually you change c/a by a few percent; i.e. 3% but not 300% !!!
>
>
> >                                     I was doing c/a optimization for an
> > A2BCO4 type compound. The optimize.job file was created for structures
> > having c/a 100%, 200%, 300% and 400% increased value than the input c/a..
> > The program  calculates structures having c/a 100% and 200% more than
> input
> > c/a but stopped after that by showing the following error:
> >
> > 'SETFF1' - ifft too small in xcpot3
> >  'SETFF1' - 2*(KKK+1) LARGER THAN IFFT PARAMETERS IN
> > XCPOT3
> >  'SETFF1' - KKK=   0   0
> > 45
> >  'SETFF1' - IIx=   0   0
> > 45
> >  'SETFF1' - IFFT= 108  96
> > 90
> >
> > I was chosen c/a value for more than 300% , 400%  than the input c/a.
> This
> > was done as I beliveed  that the compound should  have much larger c/a
> ratio
> >
> > My question is what is the meaning of this error and how to remove it.
> Any
> > response will be greatly appreciated. Thanks in advance.
> >
> > with regards,
> > --
> > Shamik Chakrabarti
> > Research Scholar
> > Dept. of Physics & Meteorology
> > Material Processing & Solid State Ionics Lab
> > IIT Kharagpur
> > Kharagpur 721302
> > INDIA
> >
>
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
> --------------------------------------------------------------------------
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-- 
Shamik Chakrabarti
Research Scholar
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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