These degenerate states, if included in the sum over k, would make the second term of Eq. ( ) diverge and are therefore explicitly excluded from the sum. The MCD signal of the D j set is instead described via the non-divergent A term and the derivative of the lineshape function (Eq. 2). Assuming a non-degenerate ground state, the exact SOS expression for the A term of an excited state j within the degenerate set D j is A(0 → j) = 1 2 ε αβζ Im