Calculation of total photoabsorption cross sections of Ar, Kr, N2 and CO Original Research Article

We present a new inversion procedure for the dispersion integral equation relating the total photoabsorption cross section to the frequency-dependent (dynamic) polarizability of an atom or molecule. Together with a reliable method to calculate the latter, this opens a way to the calculation of photoabsorption cross sections for complex molecules. We assess the reliability of the new inversion method by inverting the response functions for Ar, Kr, N2 and CO as obtained by the time-dependent second-order Møller-Plesset method and comparing with other theoretical and experimental results.