[Wien] Fermi contact chemical shift

[zhang123]

Dear Wien2K users,

 now I am going to calculate the NMR-Fermi contact
 chemical shift of Li ions in the  material (with magnetic Ni ions). In 
the spin-polarization calculation of Wien2K. we can only obtain the 
hyperfine field (HFF) near the Li nucleus. In order to get the chemical 
shift, we need to get the hyperfine coupling constant A between Li and 
Ni. The equation for A is A=u0(magnetic permability)*h(planck 
constant)*r(nucleus gyromag ration)*g(electron g factor)*uB(Bohr 
magneton)*ρ(spin density at the 
nucleus)/(3S)(S is the spin quantum number of Ni)。If we obtained A, the 
we can get the Fermi contact chemical shiftδ=A*g*uB*S*(S+1)/(3*h*r*KT), where K is Boltzmann constant and T is temperature. Then the key question is to obtain the spin 
density at or near the neclues Li. So can we directly use the the spin 
density from the item "spindensities at the nucleuse(Thomson)" or  the 
difference between spin up and spin down electron density (RUP**-RDN**)in the scf file?(I have tested this, but the calculated 
chemical shift seems several orders of magnitude smaller than the 
experiment value)
 Furthermore, If there are two kinds of Ni ions 
near the Li, the situatioin is complex. There should be two coupling 
constant A1 and A2 between Li and different Ni ions. Then how to get 
these two coupling constantn , 
respectively? Can we first to let 
one magnetic ion(for example, Ni1) to be magnetic, and force other 
magnetic ion to be nonmagnetic(Ni2), and get the corresponding spin 
density near the Li nucleus  to calculate the corresponding A1 for Ni1, 
and do the similar process for Ni2 to obtain its coupling constant A2? 
I have browsed the mailing list archives and the userguide, but cannot find the answer. So I will much appreciate that if someone can help me.

Best

 regards
Zhang 


 		 	   		  
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