[Wien] Effect of a finite nucleus on electron density at the nucleus

[pieper]

I am curious about Peter's answer:

I would have expected that the problem of nuclear decay through electron 
capture is very closely related to the one of calculating hyperfine 
parameters like isomer shift or hyperfine field. At first sight the 
calculation of these parameters suffers from the same problem of a 
nuclear point charge or spin.

I did not follow the development of calculations of the isomer shift 
which is given by the total electron density at the nucleus, but for the 
hyperfine field I always considered the work of Blügel et. al (Phys. 
Rev. B, 1987, volume 35, p. 3271) to be very illuminating. They show 
that the electron spin density should be averaged over a finite volume 
and calculate the appropriate (Thomson) radius of that volume. I would 
have expected that basically the same argument works for electron 
capture.

To my knowledge this averge of the electron density is, in fact, whats 
done in Wien2k to calculate the the hyperfine fields (Fermi-contact and 
orbital)? In that case it might be useful not to take the electron 
density at the innermost mesh point, but the sin-up and -down densities 
calculated for the hyperfine fields.

Best regards,

Martin Pieper




Am 17.01.2014 14:32, schrieb Peter Blaha:
> In principle you are absolutely right. The question is only, for wich
> property does it really matter.
> 
> At the moment I do not have plans to put a finite nucleus into the code 
> myself.
> 



> On 01/17/2014 01:03 PM, Amlan Ray wrote:
>> Dear Prof. Blaha,
>> I use WIEN2K code for calculating electron density at the nucleus to
>> determine the change of electron capture nuclear decay rate in 
>> different
>> environments. WIEN2K uses a point nucleus and I use the value of the
>> electron density at the first mesh point as given by the code. I am
>> interested to know the effect of the finite size of the nucleus on the
>> electron density at the nucleus. Since Dirac wavefunction of
>> s-electron becomes infinity at r=0 for a point nucleus, the effect of
>> considering a finite nucleus could be significant for calculating the
>> electron density at the nucleus.
>> I was wondering if the effect of a finite nucleus might be included in
>> an upcoming version of WIEN2K. Please let me know if there is any such
>> plan.
>> With best regards
>> Amlan Ray
>> Variable Energy Cyclotron Center
>> Kolkata, India
>> 
>> 
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