In a commonly made approximation, one can assume the electronic free energy F el (R) to be R-independent, which means all orientations are equally likely, and that ⟨B ind ⟩ el (R) = -σ T B 0 . This leads to the commonly known result that the chemical shift in solution is equal to one third of the trace of the chemical shielding tensor σ. Note that the order of averaging implied by Eq. ( ) (first electronic, then orientational) is exact, and does not depend on a separation of timescales (which would be problematic, because rotations and electronic relaxation can happen on similar timescales).