Computational Electron Paramagnetic Resonance SpectroscopyReference Module in Chemistry, Molecular Sciences and Chemical Engineering

In this article, we want to review computational approach to the interpretation of EPR observables. We shall limit our discussion only to cw-EPR spectroscopy, leaving out, by necessity, advanced EPR spectroscopies like time domain multiple-pulse spin echo and double resonance methods. Also, we shall address here only examples and systems for which a clear separation can be drawn between fast local motions of solvent-related properties and large-amplitude molecular relaxation processes. Within this hypothesis, which actually can be said to encompass most experimental situations, averaging of magnetic properties with respect to rapidly relaxing solvent local motions is allowed, thus implying that constant principal values of all involved magnetic tensors can be used in the SLE per se. A relevant exception is given by highly polar and protic solvents, like water and ethanol, where the presence of specific directional H-bonds may lead to a residual explicit dynamic dependence of the magnetic properties from local solvent coordinates (e.g., the average number of H-bonds) to be included in the SLE