Faraday Effect and Spin‐Orbit Interaction of the Lowest Exciton States in Molecular Crystals

The spin‐orbit interaction of the lowest excition states of a benzene crystal is calculated with the configuration interaction included. It is shown that the mixing of singlet and triplet exciton states due to the spin‐orbit interaction is negligibly small. The Faraday effect in molecular crystals is investigated taking into account Davydov splitting with application to the lowest singlet exciton states in a benzene crystal. No account is taken here of the interaction involving lattice vibrations and the internal vibrations or of rotations of the molecule as a whole.