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

[Amlan Ray]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20140121/390cc096/attachment.htm>