[Wien] Effect of finite nucleus on the change of electron capture decay rate under compression

[Peter Blaha]

I don't have this SIC code, which gave better hyperfine fields for Fe 
(but failed miserable for another test, so it might have been accidentally).

Anyway, yes, try also LDA, as GGAs may behave strange at the nucleus.

On 01/21/2014 01:56 PM, Laurence Marks wrote:
> Interesting.
>
> Maybe relevant, maybe not. I seem to remember that conventional
> functionals do not always do a great job near the nucleus, so there can
> be errors in the high angle x-ray scattering factors. Some time ago
> there was an experimental lcore which did a better job; unfortunately I
> cannot find the reference. Peter probably has the code and, at your own
> risk, you might want to try it.
>
> Beyond that you would have to change the nuclear part of the Coulomb
> integrals in lapw0.F.
>
> ______________________________
> Laurence Marks
> Dept Mat Sci & Eng
> Northwestern University
> www.numis.northwestern.edu <http://www.numis.northwestern.edu>
> 847 491 3996
>
> On Jan 21, 2014 4:31 AM, "Amlan Ray" <amlan_ray2005 at yahoo.com
> <mailto:amlan_ray2005 at yahoo.com>> wrote:
>
>     I tried different values of R0 (R0=0.0001 BU, 0.00001 BU, 0.00004
>     BU) for calculating the electron density at the nucleus. Of course,
>     the electron density changes for different values of R0 and so the
>     predicted electron capture rate also changes. However I am not
>     trying to compare the calculated electron capture rate with the
>     experimental result. By taking a suitable average over R0, I can
>     probably get a good agreement between WIEN2K calculation and the
>     experimental result. However I am interested to calculate the rate
>     of increase of the electron density at the nucleus under
>     compression. As I compress 7BeO lattice, the fractional change of
>     the electron density at the nucleus (Delta_Lambda/Lambda) increases
>     linearly with the applied external pressure. This result was
>     obtained from both WIEN2K calculations and experiment. However the
>     slope of the staright line (Delta_Lambda/Lambda versus Pressure
>     plot) is very different for WIEN2K calculation and experimental
>     result. From WIEN2K calculation, I get
>     K_P=0.42X10^-4 (GPa)^-1, whereas expt result is K_P=(2.2+-0.1)X10^-4
>     (GPa)^-1. The calculated value of K_P is essentially independent of
>     R0. I tried different values of R0 and do not find any change in the
>     calculated value of K_P. So naturally taking average over R0 will
>     not change K_P. It is very robust. However the consideration of a
>     finite nucleus will change the character of the wave function ( both
>     radial and Z-dependence) within the nuclear volume. So I think the
>     consideration of a finite nucleus will change the calculated value
>     of K_P and it should increase the value bringing it closer to the
>     experimental number.
>     Isomer shift is not directly proportional to the electron density at
>     the nucleus and people tune the calculations using experimental
>     results. In the case of isomer shift, I am interested to know
>     how well WIEN2K calculations agree with the change of isomer shift
>     under compression. Please refer me to a suitable publication where
>     the change of isomer shift under compression has been studied.
>     With best regards
>     Amlan Ray
>     VECC, Kolkata
>     India
>
>
>
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-- 

                                       P.Blaha
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