O(o)lm=(polynomial in cos(o)) Legendre's equation X(x)m=eexp(lmx). Rn(r)=eexp(-constantz) (polynomial in r, Olm(o)=(polynomial in cos o), and Xm(x)=e (-imz) . We will look at these. Perturbation_Theory This Perturbation Theory , Quantum Mechanics, method is used to calculate potenials which are varing. This method is based on some recursion relation. This will be expanded. Identical_Particles