Add formFactor method to MagneticIon class

[Martyn Gigg]

It will allow the calculation of the form factor using the Freeman-Watson parameterization

[Martyn Gigg]

Tidy up of MagneticIon code. Refs #5610

Changes made to better encapsulate the static map and tidy up the code before implementing the formFactor calculation.

Changeset: 90a84e5eb2de2c66a099f227783cd093751930f5

[Martyn Gigg]

Comments from Andrei

Make sure that you allow something more than what is described on the site that you have sent. That does not include orbital angular momentum, or anisotropy factors. What I suggest is that you call these methods something like AnalyticalJL(std::string symbol, uint16_t charge, uint16_t L, double s). For more general forms for magnetic form factors, which include higher order terms (very significant for about 50% of the cases) see ​http://neutrons.phy.bnl.gov/presentations/MagneticNeutronScattering_proofed_indexed_unlinked.pdf In particular, formulas 2.45,2.52,2.36 for dipole approximation, and 2.59, 2.60 for anisotropic form factors. At least make sure that you don't call your function MagneticFormFactor.

[Martyn Gigg]

Add simple magnetic form factor calculation + interplation table. Refs #5610

Only includes J=0 & L=0 terms but interface takes j & l as parameters so additions can be made.

Changeset: b0333a2729930fd4913c0a9ec57993e267ce5fb4

[Martyn Gigg]

Tidy up of MagneticIon code. Refs #5610

Changes made to better encapsulate the static map and tidy up the code before implementing the formFactor calculation.

Changeset: 90a84e5eb2de2c66a099f227783cd093751930f5

[Stuart Campbell]

This ticket has been transferred to github issue ​6456