Different from the SAM, the spin-split branches suggest a parallel OAM between orbital polarization and the momentum, with the ( 𝐿𝑧 ) always carrying opposite signs at the +𝑘 𝑦 and -𝑘 𝑦 points, respectively. Although the OAM energy is generally much weaker than SAM, it is enough to interact with right or left circularly polarized light to give reasonable circular dichroism (CD) signals. Moreover, our calculations show that L-DOPA and D-DOPA carry opposite OAM along the same momentum direction when projecting to the LUMO orbital (O 2p) indicating that the movements of electrons along the [111] direction are following different helical wavefronts(Fig. ). This results in the change of the lowest unoccupied molecular orbital (LUMO) when forming bonding with PdGa. Most importantly, the energy shift of LUMO is closely related to the sign of OAM or the chirality of the PdGa. This will change the energy gap between the highest occupied molecular orbital (HOMO) and LUMO, resulting in the chirality-dependent binding energies of DOPA when forming antibonding states with O 2p orbitals. This will finally result in the enantiomeric adsorption and oxidation depending on the compatibility of the OAM with each other.