• QED
• Coupled Cluster

In this thesis the possibility of discriminating between enantiomers using circularly polarized light is investigated. The discriminating effect is enanhaced in the strong coupling regime; for instance inside a self polarizing cavity.
The key features of the multipolar Hamiltonian are highlighted and the necessity for approximations is emphasized.
Since dipole Hamiltonian can not describe enantiomer discriminating interactions, quadrupole terms were retained too in the multipolar expansion leading to the definition of a quadrupole Hamiltonian. To solve the ground state problem, an ab-initio QED-HF method has been developed and implemented; a concise but detailed analysis of the chiral discriminating terms in QED-HF is reported. In order to encorporate correlation in the wavefunction, QED-CCSD ground state equations were also outlined although not yet implemented. The QED-HF calculations performed on peroxide and proline show an orientational dependence of the energy related to the enantiomer type and to the polarization of the cavity. Initial exploration of relative orientational effect in reactions producing chiral molecules have also been investigated. The results show that the effect can be significant. This will open to the possibility of using chiral cavities to drive molecular reactions.