Differential equations -- Propagators and second quantization -- The Huckel model -- Electron field operators -- Angular momentum -- Double-time Green's functions -- The electron propagator -- Electrons in a central potential -- Electron propagator -- The WKB propagator -- The atomic central field problem -- Electron propagator -- Hartree-Fock equations -- Complex spectra -- Single subshell approximation -- Approximate atomic transition amplitudes -- The hydrogen atom -- The carbon and nitrogen atoms -- The excitation propagator -- Antisymmetrized geminal power -- Interaction of radiation and matter -- A charged particle in an electromagnetic field -- Quantization of the radiation field -- Absorption spectroscopy -- RPA transition moments -- Optical rotatory dispersion and circular dichroism -- Temperature-Dependent theory -- Molecules in magnetic fields -- Nuclear spins -- Magnetic susceptibility -- NMR-Spectra -- Indirect nuclear Spin-Spin coupling constants -- Magnetic properties of molecules -- Diamagnetic molecules -- Units and magnitude of magnetic susceptibilities -- Paramagnetic molecules -- NMR spectra and shielding -- NMR spectra and Spin-Spin coupling -- The Origin Problem -- The Gauge Problem -- Calculation of magnetic properties -- An elementary example of NMR spectra -- Paramagnetic molecules -- Electron propagator in higher orders -- Renormalization of the electron propagator -- The 2p-h TDA and the diagonal 2p-h TDA self-energy -- Partitioning and inner projections -- Method of solution