Scattering of a diatomic composite system

We investigate the scattering problem of a two-particle composite system on a delta-function potential. Using the time independent scattering theory, we study how the transmission/reflection coefficients change with the height of external potential, the incident momentum, and the strength of internal potential. In particular, we show that the existence of internal degree of freedom can significantly change the transmission/reflection coefficients even without internal excitation. We consider two scenarios: the internal degree of freedom of the incident wave is set to be in a state with even parity or odd parity, we find that the influence of a symmetric Hamiltonian is greater on the odd-parity internal states than on the even-parity ones.