Extended Stevens operators for spins S > 1/2.

Op = stev(S,k,q)

This function computes the extended Stevens operators for a spin with spin quantum number S. The parameters k and q specify the operator . Allowed values are 0<=k <= 2S and q = -k,...,k. The maximum k supported is 12, the most common values are 2, 4 and 6. For explicit expressions of the operators see the page on high-order operators.

for a spin S=2 is

stev(2,4,2)

ans =
         0         0    7.3485         0         0
         0         0         0  -12.0000         0
    7.3485         0         0         0    7.3485
         0  -12.0000         0         0         0
         0         0    7.3485         0         0

The value 7.3485 corresponds to .

The extended Stevens operators are computed using Racah's commutator rule for the components of spherical tensor operators and Ryabov's general formula for extended Stevens operators (I.D.Ryabov, J.Magn.Reson.140,141-145, 1999).

sop