[Wien] Ionic versus covalent systems

[Xu Zuo]

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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