Orthogonalization Assumption in Atomic Scattering Theory

The issue of orthogonality between initial and final state wavefunctions in the evaluation of scattering amplitudes is addressed. Over the years, various treatments of this issue may be found ranging from artificially modifying wavefunctions to ensure orthogonality to totally ignoring the issue. The assumption that initial and final states scattering wavefunctions should be orthogonal is examined for the case of electron- hydrogen scattering and it is shown that enforcing orthogonality introduces spurious effects