Status and perspectives of a virtual multifrequency spectrometer for ESR
ESR spectroscopy is still one of the most useful experimental techniques to analyze the structure, dynamics, and magnetic properties of open-shell species. However, disentanglement of the different factors tuning the overall spectra requires effective yet reliable theoretical calculations. Recent progresses in this field are very encouraging, and it is becoming often possible to compute reliable magnetic parameters as well as to simulate the whole spectra from first principles without adjustable parameters. This goal requires the proper account of different aspects concerning stereo-electronic, environmental and dynamical properties of the molecular system under investigation. Approaches rooted into the stochastic Liouville equation then provide, at present, the most effective theoretical background for integrating magnetic and dynamic ingredients to directly give the spectrum. The main topic of the present contribution is the description of a recent implementation of one of these approaches in a virtual molecular spectrometer including also a powerful graphical user interface. Nitroxide radicals will be used throughout to provide specific examples of the different topics.