Gaussian quadrature approach to the calculation of the optical constants in the vicinity of inhomogeneously broadened absorption lines

A fast numerical procedure to calculate the convolution of Gaussian and Lorentzian functions is introduced as well as its application to the approximation of experimental spectra. It is shown that these spectra can be well approximated with the method, especially in the case when the inhomogeneous and homogeneous linewidth contributions as parameters of a Voigt lineshape are of the same order of magnitude. Particularly, the method is applicable to refractive index modelling in the vicinity of inhomogeneously broadened absorption lines.