Time-correlation functions from band-shape fits without Fourier transform

A fitting method is described which enables one to model real line profiles intermediate between Lorentzian and Gaussian by an analytical function which has an analytical counterpart in the time domain. The applications of this method comprise: (1) finding time correlation functions and correlation times by fits in the frequency domain without Fourier transforms; and (2) the decomposition of overlap lines obtaining dynamic parameters at the same time.