[Pw_forum] about the core radii of Li and N

[Lorenzo Paulatto]

On Thu, January 17, 2008 15:59, wangjunjie1981_0 wrote:
>   When i genernate the pseudopotentials of Li and N atoms, respectively, i
> find that the core radius of Li atom is bigger than that of N atom in
> original ini file. But Why?

If you are referring to this ld1.x message:
       r > 0.41 : true rho core
than it's not the core size, but a radius before which real core charge is
replaced with a pseudized, softer, core charge.

You can set that radius by hand (rcore=...) or let ld1 decide where to
cut, the rule used is:
      rcore= matching radius (a.u.) for the smoothing of the core charge
             If not specified, the matching radius is determined
             by the condition  rho_core(rcore) = 2*rho_valence(rcore)

So the fact that rcore is smaller for N than for Li only means that the
ratio rho_core/rho_valence become small enough sooner for N than for Li.
In other words valence charge is higher and more localized in N than in
Li, compared to their respective core charges.

Hope it helps, goodbye.

-- 
Lorenzo Paulatto
SISSA  &  DEMOCRITOS (Trieste)
+39 040 3787 511
http://people.sissa.it/~paulatto/


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