Issue with Tb

[sivonxay]

There is an issue with Tb, where entries in the magnetic dipole matrix become NaN. To the best of my knowledge, this comes from Tb's slj values.

Code to reproduce:

from NanoParticleTools.inputs.spectral_kinetics import SpectralKinetics
from NanoParticleTools.species_data import Dopant
sk = SpectralKinetics([Dopant('Tb', 0.1, 3)])
sk.magnetic_dipole_rate_matrix

Output:

array([[0.        , 0.        , 0.        ],
       [       nan, 0.        , 0.        ],
       [0.        , 1.20341175, 0.        ]])