[Wien] Ionic versus covalent systems

[Laurence Marks]

Not 0.01, change to 0.1 -- 0.4 is too large anyway in most cases.

On Sat, Mar 15, 2008 at 7:28 PM, Xu Zuo <xzuonku at gmail.com> wrote:
> Dear Subin,
>
> You can change the parameter in case.inm from the default 0.40 to 0.01, as
> suggested by the user's guide. This works for spinel ferrites.
>
> Good Luck,
>
> Xu Zuo
>
>
>  On Fri, Mar 14, 2008 at 6:08 AM, <jadhikari at clarku.edu> wrote:
> > Dear Wien2k users,
> >
> > I did calculations of compounds containing "Calcium ions" and it was
> > extremely tough to get the converged results. The calculations of similar
> > compounds, replacing Calcium with "Lead ions" was extremely easy and of
> > course superbly fast. All that was done was "Ca" replacex with "Pb".
> >
> > So the questions ( basic) are-
> > Is it the former being more ionic we are having problems and that the
> > latter being more covalent all of the troubles are gone?
> >
> > Is is because of localized versus delocalized systems?
> >
> > Following compounds- LiZnN, LiMgN, LiMn2O4, NaNbO3, MgAl2O4, CaCu3Ti4O12
> > possess ionic characteristics and NaNbO3 is an example of a tougher system
> > for convergence. 9 IBZ with RKmax of 6 or greater is extremly time
> > consuming. The published article is silent about the RKmax and the test
> > for higher IBZ points.
> >
> > Is it because of "Na" ion in the system or it does not matter?
> >
> > Looking forward for just a general idea.
> >
> > Thanking you
> >
> > Subin Adhikari
> >
> >
> > _______________________________________________
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> > Wien at zeus.theochem.tuwien.ac.at
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> >
>
>
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>



-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Commission on Electron Diffraction of IUCR
www.numis.northwestern.edu/IUCR_CED