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

[Laurence Marks]

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
847 491 3996
On Jan 21, 2014 4:31 AM, "Amlan Ray" <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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