Electron propagator theory , open-shell

G. Bom and I. Shavitt, A Unitary Group Formulation of Open-Shell Electron Propagator Theory, J. Chem. Phys. 76, 558-567 (1982). 

The contributions of the second order terms in for the splitting in ESR is usually neglected since they are very small, and in feet they correspond to the NMR lines detected in some ESR experiments (5). However, the analysis of the second order expressions is important since it allows for the calculation of the indirect nuclear spin-spin couplings in NMR spectroscoi. These spin-spin couplings are usually calcdated via a closed shell polarization propagator (138-140), so that, the approach described here would allow for the same calculations to be performed within the electron Hopagator theory for open shell systems. 

Eshuis et al have implemented fully propagated time-dependent Hartree-Fock theory to calculate the real time electronic dynamics of closed- and open-shell molecules in strong oscillating electric fields. This method has been illustrated on the determination of the frequency-dependent polarizability of ethylene and is shown to converge, in the weak field limit, to the same results as the linearized TDHF method. 

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