Radial Functions and Orthonormality

In close analogy to the nonrelativistic theory, it is advantageous (as we shall see in the following) to introduce a second set of radial functions, P, = P ,k, 

The subscripts in Eq. (6.57) (differentiate between different sets of radial functions belonging to different states Y, (r) = T, (r, 0, q ) with the composite index 

The orthonormality of the spherical harmonics and of the spin eigenvectors psnts (with s = 1/2 and OTs = 1/2) ensures orthonormality of the Pauli spinors, 

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