# stev2sph.m

Stevens coefficients into irreducible spherical tensor coefficients.

## Syntax

    Bkq=stev2sph(k,Bkq)


## Description

Transforms the coefficients in front of Stevens operators, as produced by stevens.m, into the coefficients before the irreducible spherical tensor operators, as produced by irr_sph_ten.m function. Works up to 6th spherical rank. Source: http://dx.doi.org/10.1088/0022-3719/18/7/009

## Arguments

    k     - the spherical rank in question

Bkq   - a column of 2k+1 real coefficients
in front of Stevens operators, in
increasing order of projections


## Outputs

   Bkq   - a column of 2k+1 complex coefficients
in front of irreducible spherical
tensor operators, in decreasing order
of projections


## Examples

See the files in examples/giant_spin directory

## Notes

K.W.H. Stevens has done a great disservice to Magnetic Resonance by his ill-considered choice of basis operators for the crystal field theory he was developing. Choosing irreducible spherical tensors instead would have saved many days to nearly everybody in this field. At the moment, the community is stuck with the ridiculously bad definitions that do not follow the 3D rotation group - "for historical reasons". Someone would have created crystal field theory if Stevens hadn't - but he had poisoned it forever by doing it badly.